Systems and methods for processing gases

ABSTRACT

The invention includes a gas processing system for transforming a hydrocarbon-containing inflow gas into outflow gas products, where the system includes a gas delivery subsystem, a plasma reaction chamber, and a microwave subsystem, with the gas delivery subsystem in fluid communication with the plasma reaction chamber, so that the gas delivery subsystem directs the hydrocarbon-containing inflow gas into the plasma reaction chamber, and the microwave subsystem directs microwave energy into the plasma reaction chamber to energize the hydrocarbon-containing inflow gas, thereby forming a plasma in the plasma reaction chamber, which plasma effects the transformation of a hydrocarbon in the hydrocarbon-containing inflow gas into the outflow gas products, which comprise acetylene and hydrogen. The invention also includes methods for the use of this gas processing system.

RELATED APPLICATIONS

This application is a continuation of U.S. Application No. 17/402,937filed on Aug. 16, 2021, which is a continuation of U.S. Application No.17/155,760 filed on Jan. 22, 2021, which is a continuation-in-part ofU.S. Application No. 16/548,378 filed on Aug. 22, 2019, which claims thebenefit of U.S. Provisional Application No. 62/721,863 filed on Aug. 23,2018, U.S. Provisional Application No. 62/736,206 filed on Sep. 25,2018, and U.S. Provisional Application No. 62/793,763 filed on Jan. 17,2019; U.S. Application No. 17/155,760 also claims the benefit of U.S.Provisional Application No. 62/964,977 filed Jan. 23, 2020, U.S.Provisional Application No. 62/969,494 filed Feb. 3, 2020, U.S.Provisional Application No. 62/986,998 filed Mar. 9, 2020, and U.SProvisional Application No. 63/019,851 filed May 4, 2020, and U.S.Provisional Application No. 63/052,524, filed Jul. 16, 2020. The entireteachings of the above applications are incorporated herein byreference.

BACKGROUND

Acetylene can be used as a chemical precursor or as a feedstock forindustrial combustion uses, such as welding and metal cutting.Commercial production of acetylene has been carried out since the earlytwentieth century. The original method for acetylene production utilizedcoal as the source material, through a process involving a calciumcarbide intermediary. Other methods were developed later in thetwentieth century, mainly using heat-based processes such as thermalcracking or electric arc furnaces.

Acetylene produced from coal involves a three-step process: first, coalis heated to produce high-carbon-content coke; second, the coke isheated further in the presence of calcium oxide to yield calciumcarbide; third, calcium carbide reacts with water to yield acetylene andcalcium hydroxide. The first two steps require very high temperatures,while the last step is exothermic. This method for forming acetylene isstill used commercially, especially in China where coal is readilyavailable.

This process, however, carries the impurities of the coal and limesource materials into the final product, so that the resulting acetyleneis contaminated with impurities such as phosphines, arsines, andhydrogen sulfate. All of these species are capable of poisoningcatalysts for subsequent chemical reactions, so that they need to bescrubbed from the acetylene product before it can be used commercially.Chemical grade acetylene, used for further chemical processing, mustbe >99.6% pure C₂H₂, with < 25 ppm phosphine/arsine/H₂S. Industrialgrade acetylene, which is burned for welding and metal cuttingapplications, can tolerate more impurities (>98.0 pure C₂H₂, < 500 ppmphosphine/arsine/H₂S). Therefore, the coal-derived production ofacetylene is limited in the U.S. to forming industrial grade acetylene;still, even when coal-derived acetylene is just used for welding andmetal cutting, the presence of potentially hazardous contaminants raisesconcerns.

As an alternative, acetylene can be prepared from hydrocarbons bypartial oxidation, for example, by the process developed by BASF, asdescribed in U.S. Pat. No. 5,824,834. In this process, a hydrocarbonfeedstock and oxygen are preheated and then reacted in a combustionchamber, causing the produced gases to reach temperatures > 1500° C. Thecombustion reaction is quenched with water to effect rapid cooling,yielding a gaseous mixture (called “cleavage gas”) of acetylene,hydrogen, carbon monoxide, steam, and byproducts. This method ofacetylene production yields about 7.5% acetylene, along with largequantities of hydrogen (57%), carbon monoxide (26%), and methane (5.2%).One of the byproducts is soot, which needs to be removed from thecleavage gas as it is processed further. Other byproducts includehigher-order hydrocarbons, including alkanes, alkenes, alkynes, andaromatics. Removing the impurities from the cleavage gas and recoveringthe acetylene it contains involve significant engineering challenges.

In addition to the production issues, acetylene is difficult to handleand transport. It is highly explosive. When transported throughpipelines, it is kept at a low pressure and is only conveyed for shortdistances. Acetylene for industrial purposes is pumped into tanks athigh pressure and dissolved in solvents, for example, dimethylformamide,N-methyl-2-pyrrolidone, or acetone. When the acetylene cylinder isopened, the dissolved gas vaporizes and flows through a connecting hoseto the welding or cutting torch. The entire amount of acetylene in acylinder is not usable however, because a certain amount remainsdissolved in the solvent and is returned to the manufacturer in thisstate. With the rise of the petrochemical industry in the mid-twentiethcentury, acetylene continued to be used industrially (i.e., for welding,metal cutting and the like) but it was displaced as a precursor forchemical reactions, replaced by other feedstocks (e.g., ethylene) thatwere derived directly from oil rather than from coal. As oil has becomemore expensive and natural gas has become cheaper though, there isincreased interest in acetylene as a platform for further chemicalprocessing instead of petroleum-derived feedstocks.

Moreover, the abundance of natural gas is driving the search for moreways to use this material without burning it, to decrease its greenhousegas effects and to avoid transforming it into CO₂, another greenhousegas, by simple combustion. Besides natural gas, other mixed gas sourcessuch as oceanic clathrates, coal mine gas, and biogas contain methanegas as well. Biogas is naturally produced mixed gas source that isproduced by the anaerobic decomposition of organic waste material invarious human-created environments such as landfills, manure holdingponds, waste facilities, and the like, and in natural environments suchas peat bogs, melting permafrost, and the like. The anaerobic bacteriathat occur in such environments digest the organic material thataccumulates there to produce a gas mixture composed mainly of carbondioxide and methane. Biogas with a high methane content, as can be foundin landfill-derived gas mixtures, can be hazardous, because methane ispotentially flammable. Moreover, methane is a potent greenhouse gas.Currently biogas that is collected from organic decomposition (e.g.,landfills, waste facilities, holding ponds, and the like, or naturalregions containing decaying organic materials) can be purified to removethe CO₂ and other trace gases, resulting in a high concentration ofmethane for producing energy. However, simply burning methane-richbiogas produces CO₂, another greenhouse gas. It would be desirable toidentify uses for biogas or other mixed gas sources that can exploittheir energy potential without burning them, to decrease the greenhousegas effects of methane while avoiding transforming methane into anothergreenhouse gas, CO₂.

Increasing demand for non-hydrocarbon sources of fuel supports the useof methane as a feedstock for producing hydrogen, which in turn can beused as a source of power. Conventional technologies already exist forextracting hydrogen gas from the methane in natural gas. Steamreforming, for example, can produce hydrogen gas and carbon monoxide;the hydrogen created by the steam reforming process can then be used inpure form for other applications, such as hydrogen fuel cells or gasturbines, in which it combines with oxygen to form water, withoutgreenhouse gas emissions. Other processes, such as partial oxidation,can produce a hydrogen-rich syngas, a combustible mixture that can beused as a fuel. Conventional techniques for producing hydrogen frommethane have drawbacks, however. Steam reforming is carried out at hightemperatures, and is energy-intensive, requiring costly materials thatcan withstand the harsh reaction conditions. Steam reforming usescatalysts to effect the conversion of methane to hydrogen, but thecatalysts are vulnerable to poisoning by common contaminants. Partialoxidation is a less efficient technique than steam reforming forproducing hydrogen, being prone to soot formation, and being limited inhydrogen yield. While over 90% of hydrogen is currently produced bythermochemical processes using hydrocarbon sources, it can also beproduced by electrolysis of water and other non-carbon chemicalprocesses.

Hydrogen, a zero-emission fuel source, can be used for a variety ofcommercial applications. The majority of hydrogen is used as a feedstockfor industrial chemical processes, but it is gaining wider acceptance asa fuel source that can substitute for hydrocarbons. For example,hydrogen can power fuel cells or internal combustion, combining withoxygen in the atmosphere when it is burned. This use of hydrogen as afuel thus avoids the production of carbon-based greenhouse gases such ascarbon dioxide. Hydrogen is increasingly being used for poweringvehicles such as trucks and passenger cars, and it is already anestablished fuel for mass transit vehicles like buses. More demand forhydrogen is expected with the emergence of the so-called “hydrogeneconomy,” where hydrogen would be used as a fuel source for heatproduction, for vehicles, and for long-distance energy transportation.

There is a need in the art, therefore, for a process that utilizes mixedgas sources such as natural gas or biogas, and/or more purifiedhydrocarbon feedstocks (e.g., methane, ethane, propane, and butane, andcombinations thereof) to form higher-value products. For those processesintended to produce acetylene, it would be advantageous to use mixed gassources such as natural gas or biogas, and/or more purified hydrocarbonfeedstocks (e.g., methane, ethane, propane, and butane) as a feedstock,avoiding the limitations of other mixed gas conversion processes orhydrocarbon combustion processes while taking advantage of the abundanceof these feedstock materials.

Concomitantly, there is a need in the art for a process that can produceacetylene in a convenient and cost-effective way, using mixed gassources such as natural gas or biogas, and/or more purified hydrocarbonfeedstocks. It would be especially advantageous to produce acetylenewith minimal impurities, so that it can be used safely and withoutsubstantial additional processing. Furthermore, there is further a needin the art to provide alternative fuels such as hydrogen scalably andefficiently. It would be desirable to carry out these processes in aneconomic and environmentally responsible way.

In addition, acetylene has utility as a fuel for various industrialapplications, for example, metal cutting. This use represents asignificant market, comparable in size to various petrochemical uses ofacetylene. At present, a major industrial use of acetylene is as a fuelfor oxyacetylene torches, used for cutting steel; in addition tocutting, acetylene is used in some welding, carburization, andheat-treating of steel. Oxyacetylene torches burn at a higher flametemperature (3,500° C.) than other oxy-fuel torches, such asoxy-hydrogen (3,000° C.) and oxy-propane (2,500° C.) torches, andoxyacetylene forms a smaller, more precise flame cone. These featuresallow for higher quality and more precise cutting than other comparableoxy-fuel cutting methods. Additionally, because the combustion ofacetylene requires a smaller stoichiometric ratio of oxygen than otherfuels like propane, the oxy-acetylene torches consume less oxygen thanother oxy-fuel torches, leading to lower oxygen operational costs.Finally, the lower flame temperature and higher oxygen requirements ofother hydrocarbon fuel types like oxy-propane torches allow for a higherrisk of incomplete combustion, producing hazardous carbon monoxide inthe work environment. For the aforesaid reasons, oxy-acetylene cuttingis standard in the industry for steel cutting.

However, as described previously, there are limitations in theproduction of acetylene and its transportation. Therefore, sourcingacetylene for industrial cutting is expensive and logisticallychallenging. First of all, acetylene used as a fuel for torches must betransported and stored in small metal cylinders because of the risk ofexplosion. In order to reduce the risk of explosion, the acetylene inthe cylinders is dissolved in acetone, lowering its partial pressure andthus the likelihood of explosion. Because acetone is present in thecylinders along with acetylene, the acetylene can only be drawn at lowflow rates (for example, not to exceed ⅐ of the container contents perhour), to reduce the chance of acetone being drawn into the outflow linealong with the acetylene - acetone in the gas feed can diminish flametemperatures and the quality of the cutting process. Even with low ratesof outflow, the acetylene in the cylinders can be depleted quickly; oncedepleted, a cylinder cannot be refilled on-site without extensive safetyinfrastructure and expertise, again because of the risk of explosion.Because of their small size, cylinders do not scale well for largeroperations, but instead must be connected in parallel via manifolding,adding to a project’s complexity. Also, because of the risk ofexplosion, cylinders require a number of safety precautions as they aretransported, adding costs and logistical challenges.

There remains a need in the art for a more streamlined, safe method ofsourcing acetylene. It would be desirable to circumvent the need foracetone-containing cylinders as the repository for acetylene gas that isused in metal working. For example, it would be useful to have acetylenefuel available on demand and as needed, avoiding the volume and flowrate constraints of cylinder storage. In addition, it would also beadvantageous to have acetylene produced in proximity to the point of itsuse to avoid the cylinder-specific difficulties with transportation.

Acetylene is also useful as a precursor or substrate for variouschemical reactions. One example is the manufacturing of polyvinylchloride, which is produced from vinyl chloride monomer (VCM). Twoindustrial processes are currently employed to manufacture VCM: (i) thechlorination of ethylene to form ethylene dichloride followed by thermalcracking to yield VCM and HCl; and (ii) the direct hydrochlorination ofacetylene. For this latter process, catalysts are used, for example,mercury chloride, activated carbon, ruthenium, and gold-based catalysts.This latter process, the direct hydrochlorination of acetylene, isparticularly desirable in environments where there is a plentiful andreliable source of acetylene. However, production, storage, andtransportation issues as described above affect the availability ofacetylene to be used for VCM manufacture. It would be advantageous toprovide acetylene in a convenient and cost-effective way so that it canbe readily used as a precursor for VCM manufacture. It would beespecially advantageous to provide a source of acetylene for VCMmanufacture where the acetylene has minimal impurities, so that it canbe used safely and without substantial additional processing. Inaddition, it would be advantageous to produce the acetylene for VCMmanufacture scalably and efficiently without need for complex logistics.Desirably, the process for VCM manufacturing can be integrated with aprocess for producing acetylene so that the difficulties of acetylenetransport and storage are avoided.

Another example using acetylene as a precursor for chemical reactions isthe manufacture of vitamins A and E. While acetylene is useful as afeedstock for making these vitamins and the provitamin β-Carotene andtheir chemical intermediates, its industrial use entails challenges. Asyet another example using acetylene as a precursor for chemicalmanufacture, acetylene can be decomposed to produce hydrogen gas andcarbon solids. The particulate carbon produced by this reaction, termedacetylene black, is particularly useful because its small and uniformprimary particles form long chains of carbon with excellent electricaland thermal conductivity. Because of its physical structure and purity,acetylene black is a more valuable substance than standard carbon black.It is used, for example, in the manufacture of batteries, conductivepolymers, and other specialty products.

Importing acetylene to manufacturing sites as a precursor for chemicalreactions such as those described above incurs high transportation costsdue to its explosive nature; commercial grade acetylene can containimpurities; and the material itself can be in short supply. Moreover,current techniques for producing acetylene (using calcium carbide,partial oxidation, or cracking) all have process-specific drawbacks. Itwould be advantageous to produce acetylene for vitamin manufacturing oracetylene black production with minimal impurities, so that it can beused for these processes without substantial additional processing. Inaddition, it would be advantageous to produce acetylene on-site andscalably, without the need for complex logistics, providing a supplythat is tailored to meet the manufacturer’s demand. Desirably, theprocess for vitamin manufacturing or acetylene black manufacturing canbe integrated with a process for producing acetylene so that thedifficulties of acetylene transport and storage are avoided.

Hydrogen, like acetylene, has many uses in industrial chemistry. Itsconventional production, however, involves technologies that requireconsiderable energy input, including steam methane reforming andelectrolysis. Moreover, steam methane reforming and similar industrialpractices themselves produce carbon monoxide or carbon dioxide as partof their hydrogen-forming reactions, counteracting the net environmentalgains that might flow from the use of hydrogen as a fuel instead ofhydrocarbons. It would be desirable, therefore, to produce hydrogen foruse as a zero-emissions fuel in a way that does not create additionalgreenhouse gases and that does not consume inordinate amounts of energy.

Furthermore, despite its environmental advantages, hydrogen facessignificant logistical and distribution challenges that counteract itszero-carbon footprint. Conventional thermochemical technologies forproducing hydrogen typically require large-scale industrial facilities,generally located at a distance from the ultimate user. Once it isgenerated, hydrogen must therefore be stored and/or be transportedacross long distances. Currently, the infrastructure for conveyinghydrogen from the point of production to the point of use includes a mixof pipelines, tank trucks, tube trailers, and the like as transportationmethods, all of which can add their own carbon burden to the atmosphere.In addition, hydrogen must be stored and transported as a super-cooledliquid or a highly compressed gas, with the potential for leakage andexplosion, making the industrial use of hydrogen more challenging forthe customer. It would be advantageous to produce hydrogen in asmaller-scale facility that can be installed closer to the end-user,decreasing the complexities of transporting this fuel over longdistances. It would also be advantageous to provide for on-demandproduction of hydrogen, potentially obviating the need for complexlogistics significantly.

SUMMARY OF THE INVENTION

Disclosed herein, in embodiments, are gas processing systems fortransforming a hydrocarbon-containing inflow gas into outflow gasproducts, comprising a gas delivery subsystem, a plasma reactionchamber, and a microwave subsystem, wherein the gas delivery subsystemis in fluid communication with the plasma reaction chamber and directsthe hydrocarbon-containing inflow gas into the plasma reaction chamber,wherein the microwave subsystem directs microwave energy into the plasmareaction chamber to energize the hydrocarbon-containing inflow gasthereby forming a plasma in the plasma reaction chamber, and wherein theplasma effects the transformation of a hydrocarbon in thehydrocarbon-containing inflow gas into the outflow gas products thatcomprise acetylene and hydrogen. In embodiments, thehydrocarbon-containing inflow gas can be derived from a mixed gassource, and the mixed gas source can be natural gas or a biogas; inembodiments, the hydrocarbon-containing inflow gas comprises a gasselected from the group consisting of methane, ethane, propane, andbutane, and the hydrocarbon-containing inflow gas can consistessentially of methane. In embodiments, the gas delivery subsystemcomprises a delivery conduit and a gas injector, wherein the deliveryconduit is in fluid communication with the gas injector, wherein thedelivery conduit delivers one or more gases to the gas injector, andwherein the gas injector delivers the one or more gases into the plasmareaction chamber. The delivery conduit can comprise a feed gas conveyingcircuit that delivers the hydrocarbon-containing inflow gas into the gasinjector, and the hydrocarbon-containing inflow gas can comprise methaneor can consist essentially of methane. In embodiments, the deliveryconduit comprises an additional gas conveying circuit that delivers anadditional gas into the gas injector, and the additional gas can behydrogen. In embodiments, the additional gas conveying circuit is anauxiliary gas conveying circuit that delivers an auxiliary gas into thegas injector, or the additional gas conveying circuit is a recycled gasconveying circuit that delivers a recycled gas into the gas injector.The recycled gas can comprise hydrogen, or it can comprise a hydrogenrich reactant gas, or it can consist essentially of hydrogen, or it canconsist essentially of a hydrogen rich reactant gas. In embodiments, thedelivery conduit delivers each of the one or more gases into the gasinjector through a separate pathway. In embodiments, the gas injectorcomprises an injector body comprising two or more coaxially arranged andseparate gas feeds, a first gas feed conveying thehydrocarbon-containing inflow gas into the plasma reaction chamberthrough a first set of one or more nozzles, and the second gas feedconveying the additional gas into the plasma reaction chamber through asecond set of one or more nozzles. In embodiments, at least one of theone or more nozzles is oriented at an angle to a longitudinal axis ofthe plasma reaction chamber or at an angle to a transverse axis of theplasma reaction chamber. In embodiments, at least one of the one or morenozzles is oriented at an angle to a longitudinal axis or a transverseaxis of the injector body. The combined gas flow from the first set ofnozzles and the second set of nozzles creates a vortex flow within theplasma reaction chamber. In embodiments, the plasma reaction chamber isdisposed within an elongate reactor tube having a proximal and a distalend, and the elongate reactor tube is dimensionally adapted forinteraction with the microwave subsystem. The elongate reactor tube canbe a quartz tube. The plasma reactor chamber can be disposedapproximately at the midportion of the elongate reactor tube. Inembodiments, the gas injector conveys the hydrocarbon-containing inflowgas and the additional gas into a proximal portion of the elongatereactor tube wherein the hydrocarbon-containing inflow gas and theadditional gas flow distally therefrom towards the plasma reactionchamber. The gas injector can be positioned centrally within theproximal portion, and the first set of one or more nozzles and thesecond set of one or more nozzles are oriented peripherally;alternatively, the gas injector is positioned peripherally within theproximal portion, and the first set of one or more nozzles and thesecond set of one or more nozzles are oriented centrally. Inembodiments, the microwave subsystem comprises an applicator fordirecting microwave energy towards the plasma reaction chamber, and theplasma reaction chamber is disposed in a region of the elongate reactortube that passes through the applicator and intersects itperpendicularly. The applicator can be a single-arm applicator. Inembodiments, the microwave subsystem further comprises a power supply, amagnetron, and a waveguide, whereby the power supply energizes themagnetron to produce microwave energy with the microwave energy beingconveyed by the waveguide to the applicator, and wherein the applicatordirects the microwave energy towards the reaction chamber within theelongate reactor tube, thereby forming the plasma in the plasma reactionchamber. The magnetron can produce L-band microwave energy. Inembodiments, the plasma within the plasma reaction chamber produces theoutflow gas products, and the outflow gas products flow within theplasma reaction chamber distally towards the distal end of the elongatereactor tube. The outflow products can emerge from the distal end of theelongate reactor tube to enter an effluent separation and disposalsubsystem. In embodiments, the effluent separation and disposalsubsystem can comprise a solids filter and a cold trap, and/or cancomprise an adsorption column, and/or can comprise a pressure swingadsorption system adapted for removing non-hydrogen components from aneffluent stream, and/or can comprise a temperature swing adsorptionsystem adapted for removing higher acetylenes from an effluent stream,which temperature swing adsorption system can include a regular-cycletemperature swing adsorber.

In certain embodiments, the invention is directed to system fortransforming a hydrocarbon-containing inflow gas into outflow gasproducts, comprising:

-   a gas delivery subsystem, a plasma reaction chamber, a microwave    subsystem, and an effluent separation and disposal system;-   wherein the gas delivery subsystem: i. is in fluid communication    with the plasma reaction chamber and directs one or more gases into    the plasma reaction chamber, wherein the one or more gases comprises    the hydrocarbon-containing inflow gas; and-   ii. comprises a delivery conduit and a gas injector,    -   a. wherein the delivery conduit is in fluid communication with        the gas injector, wherein the delivery conduit delivers the one        or more gases to the gas injector, and wherein the delivery        conduit comprises a feed gas conveying circuit that delivers the        hydrocarbon-containing inflow gas into the gas injector, and    -   b. wherein the gas injector delivers the one or more gases into        the plasma reaction chamber;-   wherein the plasma reaction chamber:    -   i. is in fluid communication with the effluent separation and        disposal system; and    -   ii. is disposed within an elongate reactor tube having a        proximal and a distal end, and wherein the elongate reactor tube        is dimensionally adapted for interaction with the microwave        subsystem;-   wherein the microwave subsystem:    -   i. directs microwave energy into the plasma reaction chamber to        energize the hydrocarbon-containing inflow gas, thereby forming        a plasma in the plasma reaction chamber, and wherein the plasma        effects the transformation of a hydrocarbon in the        hydrocarbon-containing inflow gas into the outflow gas products,        wherein the outflow gas products comprise acetylene and        hydrogen;    -   ii. comprises an applicator for directing microwave energy        towards the plasma reaction chamber, and wherein the plasma        reaction chamber is disposed in the region of the elongate        reactor tube that passes through the applicator and intersects        it perpendicularly; and    -   iii. further comprises a power supply, a magnetron, and a        waveguide, whereby the power supply energizes the magnetron to        produce microwave energy, the microwave energy being conveyed by        the waveguide to the applicator, and wherein the applicator        directs the microwave energy towards the reaction chamber within        the elongate reactor tube, thereby forming the plasma in the        plasma reaction chamber,

    wherein the outflow gas products flow within the plasma reaction    chamber towards the distal end of the elongate reactor tube and    emerge from the distal end of the elongate reactor tube forming an    effluent stream that enters the effluent separation and disposal    subsystem, and-   wherein the effluent separation and disposal system comprises a    short-cycle temperature swing adsorption system adapted for    separating the hydrogen from the effluent stream.

In embodiments, the effluent separation and disposal system comprises atemperature swing adsorption system adapted for separating hydrogen fromthe effluent stream, which temperature swing adsorption system caninclude a short-cycle temperature swing adsorber. In other embodiments,the effluent separation and disposal system comprises a regular-cycletemperature swing adsorption system adapted for separating higheracetylenes from the effluent stream and a short-cycle temperature swingadsorption system adapted for separating hydrogen from the effluentstream. In embodiments, the regular-cycle temperature swing adsorptionsystem is positioned upstream from the short-cycle temperature swingadsorption system.

In addition or alternatively, the effluent separation and disposalsubsystem can, in embodiments, comprise an absorption column which inembodiments can absorb acetylene, and/or can comprise a concentratedacid in an amount sufficient to oxidize higher-order hydrocarbons,and/or can comprise a catalyst suitable for converting higher-orderhydrocarbons into derivative compounds separable from the effluentstream, and/or can comprise a condenser, and/or can comprise a gasseparation membrane array which in embodiments can separate hydrogenfrom the effluent stream, and/or can comprise a hydrogen separationsubsystem which in embodiments can be in fluid communication with therecycled gas conveying circuit wherein hydrogen collected by thehydrogen separation subsystem is recycled into the recycled gasconveying circuit, and/or can comprise an acetylene separationsubsystem.

Further disclosed herein are methods for processing ahydrocarbon-containing inflow gas to produce acetylene gas, comprisingproviding the hydrocarbon-containing inflow gas, injecting thehydrocarbon-containing inflow gas into a reaction chamber, energizingthe hydrocarbon-containing inflow gas in the reaction chamber withmicrowave energy to create a plasma; forming gas products in the plasma,wherein one of the gas products is the acetylene gas; and flowing thegas products to exit the reaction chamber. In yet additionalembodiments, the invention encompasses a method for processing ahydrocarbon-containing inflow gas to produce outflow gas products,wherein the outflow gas products comprise acetylene and hydrogen,wherein the method comprises the steps of injecting thehydrocarbon-containing inflow gas into a plasma reaction chamber;energizing the hydrocarbon-containing inflow gas in the plasma reactionchamber with microwave energy to create a plasma; forming outflow gasproducts in the plasma, wherein the outflow gas products compriseacetylene and hydrogen; flowing the outflow gas products to exit theplasma reaction chamber; and removing hydrogen from the outflow gasproducts by short cycle temperature swing adsorption. In embodiments,the hydrocarbon-containing inflow gas is derived from a mixed gassource; the mixed gas source can be natural gas or a biogas. Inembodiments, the hydrocarbon-containing inflow gas comprises a gasselected from the group consisting of methane, ethane, propane, andbutane, and it can consist essentially of methane. In certain practices,the method further comprises the step of providing one or moreadditional gases concomitant with the step of providing thehydrocarbon-containing inflow gas, and the one or more additional gasescan be selected from the group consisting of hydrogen, nitrogen, and arecycled gas. In embodiments, the recycled gas comprises a hydrogen-richreactant gas, which can consist essentially of hydrogen. In certainpractices, the method further comprises the step of segregatingacetylene gas from the outflow gas products following the step offlowing the gas products to exit the reaction chamber. In yet furtheraspects, the method further comprises the step of segregating acetylenegas from the outflow gas products following the step of removinghydrogen from the outflow gas products by short cycle temperature swingadsorption. In certain practices, the method further comprises the stepof recycling at least one of the gas products. In embodiments, the atleast one gas product can comprise hydrogen gas, or can consistessentially of hydrogen gas.

Also disclosed herein are methods for transforming ahydrocarbon-containing inflow gas into an outflow gas, comprisingproviding the hydrocarbon-containing inflow gas, directing thehydrocarbon-containing inflow gas into the gas processing system asdescribed above, and processing the hydrocarbon-containing inflow gasusing the gas processing system described above to transform the inflowgas into the outflow gas, wherein the outflow gas comprises acetylene.In embodiments, the hydrocarbon-containing inflow gas is derived from amixed gas source, and the mixed gas source can be natural gas or abiogas. In embodiments, the outflow gas further comprises hydrogen. Inaddition, the invention encompasses a method for transforming ahydrocarbon-containing inflow gas into outflow gas products, comprising:providing one or more gases, wherein the one or more gases comprises thehydrocarbon-containing inflow gas; directing the hydrocarbon-containinginflow gas into the system described herein, wherein the deliveryconduit delivers the one or more gases to the gas injector, wherein thegas injector delivers the one or more gases into the plasma reactionchamber; wherein the microwave subsystem directs microwave energy intothe plasma reaction chamber to transform the one or more gases into theplasma and wherein the plasma effects the transformation of ahydrocarbon in the hydrocarbon-containing inflow gas into the outflowgas products; wherein the outflow gas products flow within the plasmareaction chamber towards the distal end of the elongate reactor tube andemerge from the distal end of the elongate reactor tube forming aneffluent stream that enters the effluent separation and disposalsubsystem; and wherein the short-cycle temperature swing adsorptionsystem removes hydrogen from the effluent stream.

Disclosed herein, in addition, are metal-cutting systems, comprising thegas processing system as described herein, and a storage system forcontaining the outflow gas products produced by the system; and anapparatus for metal-cutting in fluid communication with the storagesystem, wherein the apparatus draws the outflow gas products from thestorage system and ignites them for use in metal cutting. Inembodiments, the apparatus is an acetylene torch or an oxyacetylenetorch. In embodiments, the metal-cutting system further comprises ahydrogen separation system in fluid communication with the gasprocessing system as described above, wherein the outflow gas flows intothe hydrogen separation system, wherein the hydrogen separation systemseparates the outflow gas into two product streams, wherein one productstream is an acetylene-rich gas; and wherein the apparatus for metalcutting uses the acetylene-rich gas stored in the storage system as fuelfor metal cutting.

Also disclosed are gas processing systems and methods for transforming ahydrocarbon-containing inflow gas into a vinyl chloride monomer (VCM).The invention encompasses a system for transforming ahydrocarbon-containing inflow gas into a VCM (vinyl chloridemonomer)-containing liquid product, comprising:

-   a gas delivery subsystem, a plasma reaction chamber, a microwave    subsystem, and a VCM reactor and separator subsystem;-   wherein the gas delivery subsystem:    -   i. is in fluid communication with the plasma reaction chamber        and directs one or more gases into the plasma reaction chamber,        wherein the one or more gases comprises the        hydrocarbon-containing inflow gas; and    -   ii. comprises a delivery conduit and a gas injector,        -   a. wherein the delivery conduit is in fluid communication            with the gas injector, wherein the delivery conduit delivers            the one or more gases to the gas injector, and wherein the            delivery conduit comprises a feed gas conveying circuit that            delivers the hydrocarbon-containing inflow gas into the gas            injector, and        -   b. wherein the gas injector delivers the one or more gases            into the plasma reaction chamber;-   wherein the plasma reaction chamber:    -   i. is in fluid communication with the effluent separation and        disposal system; and    -   ii. is disposed within an elongate reactor tube having a        proximal and a distal end, and wherein the elongate reactor tube        is dimensionally adapted for interaction with the microwave        subsystem;-   wherein the microwave subsystem:    -   i. directs microwave energy into the plasma reaction chamber to        energize the hydrocarbon-containing inflow gas, thereby forming        a plasma in the plasma reaction chamber, and wherein the plasma        effects the transformation of a hydrocarbon in the        hydrocarbon-containing inflow gas into outflow gas products,        wherein the outflow gas products comprise acetylene and        hydrogen;    -   ii. comprises an applicator for directing microwave energy        towards the plasma reaction chamber, and wherein the plasma        reaction chamber is disposed in the region of the elongate        reactor tube that passes through the applicator and intersects        it perpendicularly; and    -   iii. further comprises a power supply, a magnetron, and a        waveguide, whereby the power supply energizes the magnetron to        produce microwave energy, the microwave energy being conveyed by        the waveguide to the applicator, and wherein the applicator        directs the microwave energy towards the reaction chamber within        the elongate reactor tube, thereby forming the plasma in the        plasma reaction chamber, wherein the outflow gas products flow        within the plasma reaction chamber towards the distal end of the        elongate reactor tube and emerge from the distal end of the        elongate reactor tube forming an outflow stream that enters the        VCM reactor and separator subsystem, wherein the VCM reactor and        separator subsystem comprises a VCM reactor and a plurality of        separators;    -   i. wherein the plurality of separators comprise a first        separation system, a second separation system and a third        separation system;    -   ii. wherein the first separation system is in fluid        communication with the elongate reactor tube, and is an effluent        separator adapted to remove higher acetylenes and aromatics from        the outflow stream, producing a purified effluent stream to        deliver to the VCM reactor, wherein the purified effluent stream        comprises acetylene gas; and wherein:        -   (a) the VCM reactor is in fluid communication with the first            separation system and the second separation system;        -   (b) the VCM reactor receives the purified effluent stream            and directs the purified effluent stream across a catalytic            bed that reacts the acetylene gas with a stream of hydrogen            chloride gas to produce VCM; and        -   (c) the VCM reactor expels the VCM formed therein in a            gaseous VCM-containing effluent stream that is directed into            the second separation system;    -   iii. wherein the second separation system is a condensing system        comprising a compressor, a chiller, and a liquid-gas separator,        the second separation system being adapted to condense VCM into        liquid VCM and separate liquid VCM from the VCM effluent stream,        yielding the VCM-containing liquid product and a residual gas        stream; and    -   iv. wherein the residual gas stream is directed into a third        separation system in fluid communication with the second        separation system, wherein the third separation system processes        the residual gas stream to separate purified hydrogen from the        residual gas.

The invention also includes a system for transforming ahydrocarbon-containing inflow gas into a VCM (vinyl chloridemonomer)-containing liquid product, comprising:

-   a gas delivery subsystem, a plasma reaction chamber, a microwave    subsystem, and a VCM reactor and separator subsystem;-   wherein the gas delivery subsystem:    -   i. is in fluid communication with the plasma reaction chamber        and directs one or more gases into the plasma reaction chamber,        wherein the one or more gases comprises the        hydrocarbon-containing inflow gas; and    -   ii. comprises a delivery conduit and a gas injector;        -   a. wherein the delivery conduit is in fluid communication            with the gas injector, wherein the delivery conduit delivers            the one or more gases to the gas injector, and wherein the            delivery conduit comprises a feed gas conveying circuit that            delivers the hydrocarbon-containing inflow gas into the gas            injector, and        -   b. wherein the gas injector delivers the one or more gases            into the plasma reaction chamber;-   wherein the plasma reaction chamber:    -   i. is in fluid communication with the effluent separation and        disposal system; and    -   ii. is disposed within an elongate reactor tube having a        proximal and a distal end, and wherein the elongate reactor tube        is dimensionally adapted for interaction with the microwave        subsystem;-   wherein the microwave subsystem:    -   i. directs microwave energy into the plasma reaction chamber to        energize the hydrocarbon-containing inflow gas, thereby forming        a plasma in the plasma reaction chamber, and wherein the plasma        effects the transformation of a hydrocarbon in the        hydrocarbon-containing inflow gas into outflow gas products,        wherein the outflow gas products comprise acetylene and        hydrogen;    -   ii. comprises an applicator for directing microwave energy        towards the plasma reaction chamber, and wherein the plasma        reaction chamber is disposed in the region of the elongate        reactor tube that passes through the applicator and intersects        it perpendicularly; and further comprises a power supply, a        magnetron, and a waveguide, whereby the power supply energizes        the magnetron to produce microwave energy, the microwave energy        being conveyed by the waveguide to the applicator, and wherein        the applicator directs the microwave energy towards the reaction        chamber within the elongate reactor tube, thereby forming the        plasma in the plasma reaction chamber,-   wherein the outflow gas products flow within the plasma reaction    chamber towards the distal end of the elongate reactor tube and    emerge from the distal end of the elongate reactor tube forming an    outflow stream that enters the VCM reactor and separator subsystem,    wherein the VCM reactor and separator subsystem comprises a VCM    reactor and a plurality of separators;    -   i. wherein the plurality of separators comprises a first        separation system, a second separation system and a third        separation system;    -   ii. wherein the first separation system, in fluid communication        with the elongate reactor tube, is an effluent separator adapted        to remove higher acetylenes and aromatics from the outflow        stream, producing a purified effluent stream comprising        acetylene gas and hydrogen;    -   iii. wherein the purified effluent stream enters the second        separation system in fluid communication with the first        separation system;    -   iv. wherein the hydrogen is separated from the purified effluent        stream, thereby producing a separate hydrogen stream and a        concentrated effluent stream comprising acetylene gas;    -   v. wherein the concentrated effluent stream is delivered to the        VCM reactor in fluid communication with the second separation        system; wherein:        -   (a) the VCM reactor receives the concentrated effluent            stream and directs the concentrated effluent stream across a            catalytic bed that reacts the acetylene gas with a stream of            hydrogen chloride gas to produce VCM; and        -   (b) the VCM reactor expels the VCM formed therein in a            gaseous VCM-containing effluent stream that is directed into            the third separation system;    -   vi. wherein the third separation system, in fluid communication        with the VCM reactor, is a condensing system comprising a        compressor, a chiller, and a liquid-gas separator, the third        separation system being adapted to condense liquid VCM and        separate it from the VCM effluent stream, yielding the liquid        VCM product and a residual gas stream.

Also described are methods of using the systems described herein toproduce a vinyl chloride monomer. In certain embodiments, the inventionis directed to a method for producing a vinyl chloride monomer,comprising providing a system described herein; processing ahydrocarbon-containing inflow gas to produce outflow gas products,wherein the outflow gas products comprise acetylene and hydrogen,wherein the step of processing comprises the steps of: injecting thehydrocarbon-containing inflow gas into the plasma reaction chamber;energizing the hydrocarbon-containing inflow gas in the plasma reactionchamber with microwave energy to create a plasma; forming outflow gasproducts in the plasma, wherein the outflow gas products compriseacetylene and hydrogen; flowing the outflow gas products to exit theplasma reaction chamber; and processing the acetylene thereby producedin the VCM reactor and separator subsystem in fluid communication withthe plasma reaction chamber, wherein the VCM reactor combines theacetylene with hydrogen chloride gas to form VCM in the gas by acatalytic reaction within the VCM reactor, and wherein the catalyticreaction proceeds by exposing the acetylene and hydrogen chloride gas toa catalyst within the VCM reactor.

The invention also includes a method for transforming ahydrocarbon-containing inflow gas into a VCM (vinyl chloridemonomer)-containing liquid product, comprising providing one or moregases, wherein the one or more gases comprises thehydrocarbon-containing inflow gas; directing the one or more gases intothe system described herein, wherein the delivery conduit delivers theone or more gases to the gas injector, wherein the gas injector deliversthe one or more gases into the plasma reaction chamber, wherein themicrowave subsystem directs microwave energy into the plasma reactionchamber to transform the one or more gases into a plasma and wherein theplasma effects the transformation of a hydrocarbon in thehydrocarbon-containing inflow gas into the outflow gas products; whereinthe outflow gas products flow within the plasma reaction chamber towardsthe distal end of the elongate reactor tube and emerge from the distalend of the elongate reactor tube forming an effluent stream that entersthe VCM reactor and separator subsystem; wherein the outflow gasproducts comprise acetylene and hydrogen; and wherein the VCM reactorand separator subsystem is in fluid communication with the elongatereactor tube; combining acetylene with hydrogen chloride in the VCMreactor to form a VCM-containing gas; and separating the VCM from theVCM-containing gas as a VCM-containing liquid product.

In yet additional aspects, the invention includes a method forprocessing a hydrocarbon-containing inflow gas into a VCM (vinylchloride monomer)-containing liquid product, the method comprising thesteps of: injecting the hydrocarbon-containing inflow gas into a plasmareaction chamber; energizing the hydrocarbon-containing inflow gas inthe plasma reaction chamber with microwave energy to create a plasma;forming outflow gas products in the plasma, wherein the outflow gasproducts comprise acetylene and hydrogen; flowing the outflow gasproducts to exit the plasma reaction chamber and enter a VCM andseparator subsystem, wherein the VCM and separator subsystem is in fluidcommunication with the plasma reaction chamber, wherein the VCM andseparator subsystem comprises a VCM reactor, and wherein the outflow gasproducts comprise acetylene and hydrogen; combining acetylene withhydrogen chloride in the VCM reactor to form a VCM-containing gas; andseparating the VCM from the VCM-containing gas as a VCM-containingliquid product.

The invention also encompasses an integrated acetylene-based vitaminsynthesis system for synthesizing a vitamin product (including but notlimited to Vitamin A, Vitamin E, b-carotene, or a combination thereof)comprising:

-   a plasma-based hydrocarbon processing system and a vitamin    manufacturing system,-   wherein the plasma-based hydrocarbon processing system comprises a    gas delivery subsystem, a plasma reaction chamber, a microwave    subsystem, and a set of separator subsystems,-   wherein the gas delivery subsystem:    -   i. is in fluid communication with the plasma reaction chamber        and directs one or more gases into the plasma reaction chamber,        wherein the one or more gases comprises the        hydrocarbon-containing inflow gas; and    -   ii. comprises a delivery conduit and a gas injector,        -   a. wherein the delivery conduit is in fluid communication            with the gas injector, wherein the delivery conduit delivers            the one or more gases to the gas injector, and wherein the            delivery conduit comprises a feed gas conveying circuit that            delivers the hydrocarbon-containing inflow gas into the gas            injector, and        -   b. wherein the gas injector delivers the one or more gases            into the plasma reaction chamber;-   wherein the plasma reaction chamber:    -   i. is in fluid communication with the effluent separation and        disposal system; and    -   ii. is disposed within an elongate reactor tube having a        proximal and a distal end, and wherein the elongate reactor tube        is dimensionally adapted for interaction with the microwave        subsystem;-   wherein the microwave subsystem:    -   i. directs microwave energy into the plasma reaction chamber to        energize the hydrocarbon-containing inflow gas, thereby forming        a plasma in the plasma reaction chamber, and wherein the plasma        effects the transformation of a hydrocarbon in the        hydrocarbon-containing inflow gas into outflow gas products,        wherein the outflow gas products comprise acetylene and        hydrogen;    -   ii. comprises an applicator for directing microwave energy        towards the plasma reaction chamber, and wherein the plasma        reaction chamber is disposed in the region of the elongate        reactor tube that passes through the applicator and intersects        it perpendicularly; and    -   iii. further comprises a power supply, a magnetron, and a        waveguide, whereby the power supply energizes the magnetron to        produce microwave energy, the microwave energy being conveyed by        the waveguide to the applicator, and wherein the applicator        directs the microwave energy towards the reaction chamber within        the elongate reactor tube, thereby forming the plasma in the        plasma reaction chamber,-   wherein the outflow gas products flow within the plasma reaction    chamber towards the distal end of the elongate reactor tube and    emerge from the distal end of the elongate reactor tube forming an    outflow stream that enters the set of separator subsystems;    -   i. wherein the set of separator subsystems comprises an effluent        separator, an acetylene separator, and a hydrogen separator;    -   ii. wherein the effluent separator is in fluid communication        with the elongate reactor tube, and is adapted to remove higher        acetylenes and aromatics from the outflow stream, producing a        purified effluent stream comprising acetylene gas and hydrogen;    -   iii. wherein the acetylene separator is in fluid communication        with the effluent separator, and separates a purified acetylene        product from the purified effluent stream, thereby forming a        remaining effluent stream, and wherein the acetylene separator        is in fluid communication with the vitamin manufacturing system        and directs at least a portion of the purified acetylene product        into the vitamin manufacturing system; and    -   iv. wherein acetylene separator is further in fluid        communication with the hydrogen separator and directs the        remaining effluent stream into the hydrogen separator, wherein        the hydrogen separator separates hydrogen from the remaining        effluent stream, producing a purified hydrogen product;    -   v. wherein the hydrogen separator is also in fluid communication        with the vitamin manufacturing system and directs at least a        portion of the purified hydrogen product into the vitamin        manufacturing system; and-   wherein the vitamin manufacturing system comprises a vitamin    reaction plant and a controller, whereby the controller regulates    entry of the portion of purified acetylene product and the portion    of purified hydrogen product into the vitamin reaction plant, and    wherein the vitamin reaction plant synthesizes the vitamin product    using the purified acetylene product and/or the purified hydrogen    product.

The invention also includes a method for synthesizing a vitamin product,comprising use of the integrated acetylene-based vitamin synthesissystem for synthesizing a vitamin product. In certain embodiments, theinventive method comprises:

-   i. processing a hydrocarbon-containing inflow gas to produce outflow    gas products using the system described herein, wherein the outflow    gas products comprise acetylene and hydrogen, wherein the step of    processing comprises the steps of:    -   a. injecting the hydrocarbon-containing inflow gas into the        plasma reaction chamber;    -   b. energizing the hydrocarbon-containing inflow gas in the        plasma reaction chamber with microwave energy to create a        plasma;    -   c. forming outflow gas products in the plasma, wherein the        outflow gas products comprise acetylene and hydrogen;    -   d. flowing the outflow gas products to exit the plasma reaction        chamber;-   ii. separating the outflow gas products into a set of gas streams,    the set of gas streams comprising a first gas stream comprising    higher acetylenes and aromatic impurities, a second gas stream    comprising purified acetylene, and a third gas stream comprising    purified hydrogen;-   iii. directing the second gas stream comprising purified acetylene    into the vitamin manufacturing system; and-   iv. synthesizing the vitamin product from the purified acetylene.

The invention also encompasses an integrated acetylene-based synthesissystem for synthesizing acetylene black, comprising:

-   a plasma-based hydrocarbon processing system and an acetylene-black    manufacturing system,    -   wherein the plasma-based hydrocarbon processing system comprises        a gas delivery subsystem, a plasma reaction chamber, a microwave        subsystem, and a set of separation and purification subsystems,    -   wherein the gas delivery subsystem:        -   i. is in fluid communication with the plasma reaction            chamber and directs one or more gases into the plasma            reaction chamber, wherein the one or more gases comprises            the hydrocarbon-containing inflow gas; and        -   ii. comprises a delivery conduit and a gas injector,-   wherein the delivery conduit is in fluid communication with the gas    injector, wherein the delivery conduit delivers the one or more    gases to the gas injector, and wherein the delivery conduit    comprises a feed gas conveying circuit that delivers the    hydrocarbon-containing inflow gas into the gas injector, and wherein    the gas injector delivers the one or more gases into the plasma    reaction chamber;-   wherein the plasma reaction chamber:    -   i. is in fluid communication with the effluent separation and        disposal system; and    -   ii. is disposed within an elongate reactor tube having a        proximal and a distal end, and wherein the elongate reactor tube        is dimensionally adapted for interaction with the microwave        subsystem;-   wherein the microwave subsystem:    -   i. directs microwave energy into the plasma reaction chamber to        energize the hydrocarbon-containing inflow gas, thereby forming        a plasma in the plasma reaction chamber, and wherein the plasma        effects the transformation of a hydrocarbon in the        hydrocarbon-containing inflow gas into outflow gas products,        wherein the outflow gas products comprise acetylene and        hydrogen;    -   ii. comprises an applicator for directing microwave energy        towards the plasma reaction chamber, and wherein the plasma        reaction chamber is disposed in the region of the elongate        reactor tube that passes through the applicator and intersects        it perpendicularly; and    -   iii. further comprises a power supply, a magnetron, and a        waveguide, whereby the power supply energizes the magnetron to        produce microwave energy, the microwave energy being conveyed by        the waveguide to the applicator, and wherein the applicator        directs the microwave energy towards the reaction chamber within        the elongate reactor tube, thereby forming the plasma in the        plasma reaction chamber,-   wherein the outflow gas products flow within the plasma reaction    chamber towards the distal end of the elongate reactor tube and    emerge from the distal end of the elongate reactor tube forming an    outflow stream that enters the set of separation and purification    subsystems;    -   i. wherein the set of separation and purification subsystems        comprises an acetylene separator in fluid communication with the        elongate reactor tube, adapted to remove higher acetylenes and        aromatics from the outflow stream, producing a purified effluent        stream comprising acetylene gas and hydrogen and an offgas        stream comprising higher acetylenes and aromatics;    -   ii. wherein the set of separation and purification subsystems        further comprises a hydrogen separator in fluid communication        with the elongate reactor tube, wherein the hydrogen separator        separates hydrogen as a hydrogen stream from at least one of the        outflow stream and the purified effluent stream; and    -   iii. wherein the set of separation and purification subsystems        produces an acetylene-rich feedstock stream; and-   an acetylene-black manufacturing subsystem, wherein the    acetylene-black manufacturing system comprises an acetylene    decomposition reactor in fluid communication with the separation and    purification subsystems, and wherein the acetylene decomposition    reactor produces acetylene black and hydrogen from the    acetylene-rich feedstock stream produced by the separation and    purification subsystems.

The invention also includes a method for synthesizing acetylene blackcomprising use of the integrated acetylene-based system as describedherein. In certain embodiments, the inventive method comprises:

-   i. providing the integrated acetylene-based system as described    herein,-   ii. processing a hydrocarbon-containing inflow gas to produce    outflow gas products using the integrated acetylene-based system,    wherein the outflow gas products comprise acetylene and hydrogen,    wherein the step of processing comprises the steps of:    -   a. injecting the hydrocarbon-containing inflow gas into the        plasma reaction chamber;    -   b. energizing the hydrocarbon-containing inflow gas in the        plasma reaction chamber with microwave energy to create a        plasma;    -   c. forming outflow gas products in the plasma, wherein the        outflow gas products comprise acetylene and hydrogen;    -   d. flowing the outflow gas products to exit the plasma reaction        chamber;-   iii. separating the outflow gas products into a set of gas streams,    the set of gas streams comprising a first gas stream comprising    higher acetylenes and aromatic impurities, a second gas stream    comprising purified acetylene, and a third gas stream comprising    purified hydrogen;-   iv. directing the second gas stream comprising purified acetylene    into the acetylene-black manufacturing system; and-   v. synthesizing the acetylene black from the purified acetylene.

The invention additionally includes an integrated acetylene-basedsynthesis system for producing hydrogen, the system comprising aplasma-based hydrocarbon processing subsystem and an acetylene-blackmanufacturing subsystem:

-   a. wherein the plasma-based hydrocarbon processing subsystem    comprises a gas delivery subsystem, a plasma reaction chamber, a    microwave subsystem, and a set of separation and purification    subsystems,    -   wherein the gas delivery subsystem:        -   i. is in fluid communication with the plasma reaction            chamber and directs one or more gases into the plasma            reaction chamber, wherein the one or more gases comprises            the hydrocarbon-containing inflow gas; and        -   ii. comprises a delivery conduit and a gas injector, wherein            the delivery conduit is in fluid communication with the gas            injector,-   wherein the delivery conduit delivers the one or more gases to the    gas injector, and wherein the delivery conduit comprises a feed gas    conveying circuit that delivers the hydrocarbon-containing inflow    gas into the gas injector, and wherein the gas injector delivers the    one or more gases into the plasma reaction chamber;-   wherein the plasma reaction chamber:    -   i. is in fluid communication with the set of separation and        purification subsystems; and    -   ii. is disposed within an elongate reactor tube having a        proximal and a distal end, and wherein the elongate reactor tube        is dimensionally adapted for interaction with the microwave        subsystem;-   wherein the microwave subsystem:    -   i. directs microwave energy into the plasma reaction chamber to        energize the hydrocarbon-containing inflow gas, thereby forming        a plasma in the plasma reaction chamber, and wherein the plasma        effects the transformation of a hydrocarbon in the        hydrocarbon-containing inflow gas into outflow gas products,        wherein the outflow gas products comprise acetylene and        hydrogen;    -   ii. comprises an applicator for directing microwave energy        towards the plasma reaction chamber, and wherein the plasma        reaction chamber is disposed in the region of the elongate        reactor tube that passes through the applicator and intersects        it perpendicularly; and    -   iii. further comprises a power supply, a magnetron, and a        waveguide, whereby the power supply energizes the magnetron to        produce microwave energy, the microwave energy being conveyed by        the waveguide to the applicator, and wherein the applicator        directs the microwave energy towards the reaction chamber within        the elongate reactor tube, thereby forming the plasma in the        plasma reaction chamber,-   wherein the outflow gas products flow within the plasma reaction    chamber towards the distal end of the elongate reactor tube and    emerge from the distal end of the elongate reactor tube forming an    outflow stream that enters the set of separation and purification    subsystems; wherein the set of separation and purification    subsystems:    -   i. comprises, in fluid communication with the elongate reactor        tube, an effluent separator that removes higher acetylenes and        aromatics from the outflow stream, producing (a) a purified        effluent stream comprising acetylene gas and hydrogen and (b) an        offgas stream comprising higher acetylenes and aromatic        impurities;    -   ii. further comprises, in fluid communication with the effluent        separator, an acetylene separator which produces an        acetylene-rich feedstock stream and a remaining effluent stream        as separate streams;    -   iii. further comprises a hydrogen separator in fluid        communication with the acetylene separator, wherein the hydrogen        separator separates hydrogen as a purified hydrogen stream from        the remaining effluent stream,        -   1. wherein the hydrogen stream is separable into one or more            of a recycled hydrogen stream, an integrated hydrogen            stream, and an external hydrogen stream,        -   2. wherein the external hydrogen stream is isolated from the            integrated acetylene-based synthesis system as a first            isolated hydrogen stream; and-   b. wherein:    -   i. the acetylene-black manufacturing system comprises an        acetylene decomposition reactor in fluid communication with the        set of separation and purification subsystems;    -   ii. the acetylene decomposition reactor produces acetylene black        and hydrogen from the acetylene-rich feedstock stream, and    -   iii. the hydrogen produced by the acetylene decomposition        reactor is separable from the integrated acetylene-based        synthesis system as a second isolated hydrogen stream.

The invention also encompasses a method for producing hydrogen,comprising:

-   a. providing the integrated acetylene-based synthesis system as    described above,-   b. processing a hydrocarbon-containing inflow gas to produce outflow    gas products using the plasma-based hydrocarbon processing    subsystem, wherein the outflow gas products comprise acetylene and    hydrogen, wherein the step of processing comprises the steps of:    -   i. injecting the hydrocarbon-containing inflow gas into the        plasma reaction chamber;    -   ii. energizing the hydrocarbon-containing inflow gas in the        plasma reaction chamber with microwave energy to create a        plasma;    -   iii. forming outflow gas products in the plasma, wherein the        outflow gas products comprise acetylene and hydrogen;    -   iv. flowing the outflow gas products to exit the plasma reaction        chamber;    -   c. separating the outflow gas products into a set of gas        streams, the set of gas streams comprising a first gas stream        comprising higher acetylenes and aromatic impurities, a second        gas stream that is the purified hydrogen stream, and a third gas        stream that is the acetylene-rich feedstock stream; wherein the        step of separating the outflow products further comprises a        substep of effluent separation to remove higher acetylenes from        the first gas stream, and a step of acetylene separation to        remove purified acetylene from the third gas stream;    -   d. isolating at least a portion of the purified hydrogen stream        as a first isolated hydrogen stream;    -   e. directing the acetylene-rich feedstock stream into the        acetylene-black manufacturing subsystem and producing hydrogen        and acetylene black therefrom; and    -   f. isolating at least a portion of the hydrogen from step e as a        second isolated hydrogen stream.

In certain embodiments, the systems and methods described herein furthercomprises a vacuum subsystem that maintains a first reduced pressureenvironment for the outflow products passing through one or morecomponents of the effluent separation and disposal subsystem. The vacuumsubsystem can produce a second reduced pressure environment within theelongate reactor tube, and/or it can produce a third reduced pressureenvironment for the gas delivery subsystem. In embodiments, the vacuumsubsystem produces a first, second, and third reduced pressureenvironment; in embodiments, the first, second, and third reducedpressure environments are within a range of about 30 to about 120 Torr.In embodiments, at least one of the reduced pressure environments isbetween about 50 to about 100 Torr, or is between about 60 to about 80Torr. In embodiments, the first, second, and third reduced pressureenvironments are substantially similar. The pressures in the first,second, and third reduced pressure environments are “substantiallysimilar” when each of the pressures differ by less than about 10%, orless than about 5%. For example, if the pressure in the first reducedpressure environment is 70 Torr, the pressure in the second reducedpressure environment is 67 Torr, and the pressure in the third reducedpressure environment is 70 Torr then the pressures are substantiallysimilar. In embodiments, the first reduced pressure environment has apressure that is substantially higher than the pressure in the secondand/or third reduced pressure environments. A pressure in the firstreduced pressure environment is “substantially higher” than the pressurein the second and/or third reduced pressure environment, when thepressure is the first reduced pressure environment is at least about 10%greater, or at least about 15% greater, or at least about 20% greaterthan that of the second and/or the third reduced pressure environment.In certain embodiments, the first reduced pressure environment has apressure between about 120 and about 280 Torr. In additionalembodiments, the second and/or third reduced pressure environments havea pressure in a range between about 120 and about 280 Torr, while thefirst reduced pressure environment can have a pressure that is in thesame range or is higher. In embodiments, the system further comprises acooling subsystem. The cooling subsystem can comprise at least one of awater-cooling subsystem and a gas cooling subsystem. In embodiments, thegas cooling subsystem comprises a nitrogen-based cooling circuit, andthe nitrogen-based cooling circuit can comprise one or more enclosuresfor components of the system, whereby the one or more enclosures aresealed sufficiently to enclose nitrogen gas around the components andexclude oxygen therefrom. In embodiments, the system comprises a datamanagement and safety subsystem.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram showing various chemical reactionsinvolved in the conversion of methane into hydrogen, carbon, andhydrocarbon products.

FIG. 2 depicts schematically a plasma-based hydrocarbon processingsystem and component subsystems.

FIG. 3 depicts schematically a gas delivery subsystem.

FIG. 4A and FIG. 4B illustrate embodiments of gas injectors.

FIG. 5 , FIG. 6 , and FIG. 7 illustrate embodiments of microwavesubsystems.

FIG. 8 is a schematic showing a vacuum subsystem integrated with othersubsystems of a plasma-based hydrocarbon processing system.

FIG. 9 is a block diagram of a plasma-based hydrocarbon processingsystem and related subsystems.

FIG. 10 is a schematic diagram of a reaction chamber and its components.

FIG. 11A is a schematic diagram of a gas injector in cross-section.

FIG. 11B is a schematic diagram of a gas injector in cross-section.

FIG. 12 is a schematic diagram of a microwave subsystem.

FIG. 13 is a block diagram of a small-scale system for gas processing.

FIG. 14 is a block diagram of a small-scale system for gas processing.

FIG. 15A is a block diagram of a system for use in an integrated processfor VCM manufacture.

FIG. 15B is a block diagram of a plasma-based hydrocarbon processorsuitable for use in an integrated process for VCM manufacture.

FIG. 16 is a block diagram of a system for use in an integrated processfor VCM manufacture.

FIG. 17 is a schematic illustration of a VCM reactor suitable for use inan integrated process for VCM manufacture.

FIG. 18 shows an embodiment of a multistep synthetic pathway forproduction of Vitamins A and E and beta-carotene.

FIG. 19 shows the multistep synthetic pathway of FIG. 18 with certaindetails highlighted for clarity.

FIG. 20 is a block diagram showing steps of a process for producingvitamin products using acetylene.

FIG. 21 is a schematic diagram of an integrated system for vitaminmanufacturing.

FIG. 22 is a block diagram illustrating features of an integrated systemfor vitamin processing.

FIG. 23 is a block diagram showing steps of a process for producingacetylene black using acetylene or an acetylene-rich gas.

FIG. 24 is a block diagram showing steps of a process for producinghydrogen.

DETAILED DESCRIPTION

Disclosed herein in more detail are systems and methods for convertingC₁-C₄ hydrocarbons, including unsaturated hydrocarbons and saturatedhydrocarbons such as methane (as derived from mixed gas sources such asnatural gas or biogas for example), into hydrogen, acetylene, and othercarbon-based products. In embodiments, these systems and methods usenon-thermal plasma produced by microwave energy to effect theseconversions. In embodiments, the systems and methods disclosed hereincan be optimized (“tuned”) to maximize efficient production ofacetylene, or of hydrogen, as products that can be isolated for furthercommercialization; in other embodiments, these systems and methods canbe tuned to produce a combination of these gases for specific industrialpurposes.

1. Overview A. Non-Thermal Plasmas

Plasma, the fourth state of matter, is an ionized gas: any gas can beturned into a plasma by applying enough energy to it to create asignificant density of charged species, i.e., electrons and ions.Plasmas possess some of the properties of gases, but they differ fromthe ordinary gaseous state because they respond to both electric andmagnetic fields, properties that are due to the charged species thatexist in the plasma state. Despite having these properties, plasmas areelectrically neutral, a characteristic termed quasi-neutrality. Inaddition to the ions and free electrons from the precursor gas thatexist in the plasma, a plasma includes uncharged neutral gas species andprecursor molecules that can enter into other chemical reactions. Someweakly ionized gases do not necessarily satisfy all of the conditions ofa plasma but may still have many plasma-like qualities that influencetheir behavior. For example, many of the highpressure plasmas used inindustrial applications fall into this category.

One of the fundamental characteristics of a plasma is its temperature.Plasmas have been used in chemical and industrial applications becausethey can generate temperatures much greater than those obtained intraditional chemical engineering processes. In a plasma, energy istransferred to electrons, which in turn transfer energy to heavierparticles through collisions. Electrons have a higher temperature thanheavier particles, and an equilibrium temperature is reached thatreflects the collisional frequency and radiative processes of thevarious particles in the plasma. Those plasmas having an electrontemperature (T_(e)) that is close to that of the heavy particles’translational temperature (T₀) are defined as thermal plasmas, with gastemperatures greater than 3,000 K. By contrast, in non-thermal plasmas,highly energetic electrons can co-exist with species havingsubstantially lower temperatures. Therefore, the translationaltemperature T₀ of the non-thermal plasma can be much lower than theelectron temperature T_(e) of the plasma — T_(e) can be close to 11,600K in industrial plasmas or even higher in other types of plasmas.

The energy situation in a plasma is more complex when the plasmacontains molecules (such as H₂, N₂, or CH₄) instead of just atoms. Thesemolecules have the ability to store energy in various rotational andvibrational motions, and therefore have rotational and vibrationaltemperatures associated with them. These temperatures for such plasmasgenerally lie in between the translational and electron temperature ofthe plasma, and they can affect the behavior of the plasma and itsassociated chemistry. The techniques disclosed herein are based on theability of a non-thermal plasma to transfer the major portion of theelectrical input energy to energetic electrons in the constitutive feedgas, rather than heating the gas itself. Through electron impacts,ionization, dissociation, and excitation, charged atomic and molecularspecies (e.g., electrons, ions, radicals) are generated that canparticipate in chemical reactions.

Methane is particularly resistant to chemical conversion because of itsstability: breaking the C—H bonds in methane requires an enthalpy changeof 1664 kJ mol⁻¹. Using the techniques described below, a non-thermalplasma can be produced and harnessed to break bonds in C₁-C₄hydrocarbons, including methane bonds, and create acetylene and hydrogenmolecules with high efficiency and selectivity.

B. Microwave Plasma Generation

In embodiments, the plasma used for these systems and methods is amicrowave plasma, formed by directing microwave energy at themethane-containing feed gas, as described below in more detail. Whilemethane is used as an exemplary embodiment in this description, it isunderstood that other short-chain alkanes (e.g., ethane, propane,butane) can be used as feed gases as well, either as single gas feedgases, or in combination with each other or with methane.

The microwave plasma process described herein is a gas phase process,using gaseous reactant precursors to form desired gaseous products.Because of the very fast oscillation frequency of the electric fieldrelative to the molecular and electronic collision frequencies,microwave-generated plasmas are often in a high degree ofnon-equilibrium, meaning that electron and vibrational temperatures canbe much greater than the gas temperature. In embodiments, collisionsbetween the charged species (electrons, ions) and uncharged species(molecules, atoms, particles) in the microwave plasma transfer energy:this microwave-energized plasma supports a highly reactive chemicalenvironment because of the energy contained in the plasma’s freeelectrons. Because of the high degree of ionization of the precursorgas, the chemical dissociation and ionization of intermediates, and theelevated vibrational and excitational energies in the plasma, thedesired chemical reactions described below proceed rapidly andefficiently.

Without being bound by theory, microwave radiation is understood to actas follows to create a plasma from a gaseous precursor. When theprecursor gas (e.g., methane) is subjected to microwave radiation thatmeets or exceeds the dielectric strength of such gas, a free electron(present from background radiation or other sources) in the microwavefield region is able to gain enough energy from the microwave electricalfield in between collisions with neutral molecules that it can ionizeanother atom or molecule. The secondary ionized electron is subsequentlyaccelerated in a direction that is governed by the electric field ofmicrowave radiation, and it gains energy too until it causes anotherionization event. This process of ionization progresses throughout themicrowave field region until a steady state is reached. The final numberof electrons in the plasma is determined mainly by the electron lossprocesses of the plasma, such as diffusion, recombination, andattachment.

The systems and methods disclosed herein use C₁-C₄ hydrocarbons such asmethane as the reactant precursor gas that is subjected to microwaveradiation. Methane may be used to exemplify a reactant precursor gassuitable for use in these systems and methods.

Methane dissociation in the plasma, initiated by collisions with theenergized electrons as described above, results in the formation ofCH_(x) radicals. The major initial reaction is the breaking of the C—Hbonds in methane, with resultant formation of CH3*, CH2*, CH*, H*, andC. These radicals can recombine to form two-carbon fragments asexemplified by the following equations:

In addition, methane can combine with various radicals to formtwo-carbon fragments as exemplified by the following equations:

Besides the illustrated reactions to form two-carbon fragments andhydrogen, higher-order hydrocarbons can be formed by recombinations ofplasma-generated radicals with each other and with the precursor gas. Asused herein, the term “higher-order hydrocarbon” refers to anyhydrocarbon having 3 or more carbon atoms, whether saturated orunsaturated, including aromatics.

Furthermore, complete dehydrogenation of methane can take place,resulting in the formation of elemental carbon and hydrogen gas.Representative reactions are show in FIG. 1 . As shown in FIG. 1 , anumber of exemplary reactions producing hydrocarbons are shown withinthe dotted line, while the elemental products (hydrogen and carbon) areshown outside the dotted line.

In embodiments, parameters can be optimized to maximize acetyleneformation. In other embodiments, parameters can be optimized to maximizehydrogen formation. As a general principle, for example, if the feedgases entering the plasma reaction chamber include less hydrogen ascompared to hydrocarbon input, the output will be more hydrogen formed,potentially in combination with more carbon solids. Following thisprinciple, in order to maximize hydrogen formation, a pure hydrocarbonfeed could be used, and more of the desired hydrogen would be produced,along with a quantity of carbon solids. Factors affecting productselectivity (e.g., allowing the preferential formation of acetylene overother species, or allowing the preferential formation of hydrogen overhydrocarbon products) include, without limitation, the identity of thereactant precursor gas, the addition of other gases to the system, theflow rate of any gases entering the system, the temperature and pressurein the reactor system, the amount of microwave power and flow geometryused to create the plasma, the energy density in the reaction zone, thearrangement of the electrical field surrounding the plasma, and reactorvessel geometry and dimensions. In embodiments, static electric andmagnetic fields can be employed to influence the behavior of the plasmaand hence the product selectivity.

C. Precursor Gases

For the systems and methods disclosed herein, C₁-C₄ alkane hydrocarbons(for example, methane, ethane, propane, and butane) or other hydrocarbongases can be used alone or in combination with other gases as precursorgases. In an embodiment of these systems and methods, methane is themain precursor gas. In embodiments, it can be combined with hydrogenand/or nitrogen as it enters the plasma reaction chamber, forming asingle gas mixture that is energized to the plasma state. Inembodiments, methane enters the plasma reaction chamber through its ownset of nozzles, while other gases (such as hydrogen and/or nitrogen) areadded to the plasma reaction chamber separately, through a different setor sets of nozzles. Methane can be used in a pure state, or it can beintroduced into the system as a component of a commercially availablegas stream.

Mixed gas sources such as natural gas or biogas are particularlyadvantageous sources of this precursor gas. As used herein, the term“biogas” refers to a mixed gas produced by the anaerobic decompositionof organic waste material in various natural or manmade environments;the term “biogas” includes all those natural or man-made environments inwhich such gas-producing anaerobic decomposition can take place, e.g.,landfills, manure holding ponds, municipal waste sites, sewage treatmentfacilities, agricultural waste sites, permafrost decay, and the like.Biogas as collected or retrieved from those sites can be treated orupgraded to increase its methane content and to remove impurities, sothat it becomes especially suitable as a precursor gas for the systemsand methods disclosed herein.

Biogas, produced from raw materials such as municipal waste,agricultural waste, plant material, sewage, manure, food waste or othernatural or manmade organic sources, is typically formed in a closedsystem via the anaerobic digestion or fermentation of the organicmaterial. The first stage of this process is hydrolysis, in which theinsoluble organic polymers are broken down into sugars and amino acidsthat serve as substrates for the activity of the anaerobic acidogenicbacteria. In a second stage, these bacteria convert the sugars and aminoacids into carbon dioxide, hydrogen, ammonia, and organic acids; theacidogenic bacteria further convert the organic acids into acetic acid,ammonia and carbon dioxide. As a third stage, a separate population ofanaerobic bacteria, the methanogens, convert these fermentation productsinto methane and carbon dioxide. Biogas, containing a mixture of methaneand carbon dioxide along with gaseous byproducts such as hydrogensulfide, can be collected and treated to remove carbon dioxide and theundesirable gaseous products, leaving a gaseous mixture with a highconcentration of methane that is suitable for energy production or forfurther processing. Methane in biogas is concentrated using a process ofbiogas upgrading, resulting in a product that has similar performancecharacteristics to fossil-derived natural gas.

Processes such as water washing, adsorption, membrane separation, aminegas treatment, and the like, can be used for biogas upgrading. Upgradingprocesses can advantageously be carried out to remove oxygen from thebiogas before it is used as a gas source. Oxygen in the feed gas canrender it vulnerable to combustion; moreover, oxygen can corrodeequipment used in the plasma-based hydrocarbon processing system asdisclosed herein. Furthermore, under certain circumstances, oxygenremoval may be necessary to meet regulatory standards or other purityrequirements. A number of oxygen removal technologies are suitable foruse with biogas. As an example, oxygen can be reacted with a reducedmetal species, thus oxidizing the metal and consuming the oxygen. Theoxidized metal species will then be regenerated back to the active formby reducing the metal species by passing a hydrogen or carbon monoxidecontaining gas stream over the metal species, generating water or carbondioxide, respectively. Metal species such as palladium or nickel couldbe used to catalytically combust oxygen at >500° F. with hydrocarbonspecies mixed with the O₂. As another approach, solid scavengers can beused in a disposable fashion to trap oxygen. For example, Fe₂S₃ canreact with three molar equivalents of molecular oxygen to form rust andelemental sulfur. As yet another approach, oxygen can be separated fromother gases by molecular sieves, such as 5A or 13X molecular sieve,similar to the technology seen in air separation units (ASUs). Otherupgrading processes for biogas would be available to skilled artisansusing no more than routine experimentation. Upgraded biogas can reach apurity and quality similar to the natural gas in U.S. pipelines, and canbe used for the same purposes.

Natural gas as extracted from the earth is predominantly methane, makingit a useful source of precursor gas for these systems and methods.Typically, it also includes higher-order hydrocarbons such as ethane,propane, butane, and pentane, along with non-hydrocarbon impurities. Thetable below (Table 1) illustrates an exemplary composition of naturalgas.

TABLE 1 Methane CH₄ 70-90% Ethane C₂H₆ Propane C₃H₈ 0-20% Butane C₄H₁₀Carbon Dioxide CO₂ 0-8% Oxygen O₂ 0-0.2% Nitrogen N₂ 0-5% Hydrogensulfide H₂S 0-5% Rare gases Ar, He, Ne, Xe Trace Source:http://naturalgas.org/overview/background

Natural gas is generally processed to remove most of the non-methanecomponents before it is made available for commercial or residentialuse, so that it is almost pure methane when it is reaches the consumer.As an example, natural gas available commercially can include about 96%methane. While an extensive system of pipelines exists in the UnitedStates to bring natural gas to consumer markets after it has beenstripped of its impurities, much natural gas is found in areas that arefar from these markets and far from the pipeline infrastructure (oftentermed remote or “stranded” natural gas). In embodiments, the systemsand methods disclosed herein can be used in situ, for example at thelocation of the stranded natural gas, to convert it into acetylene andother useful products; these systems and methods accordingly offer acost-effective way to utilize this stranded natural gas as a resource.

2. Systems and Subsystems

In embodiments, the plasma-based hydrocarbon processing system asdisclosed herein can comprise six subsystems: 1) a gas deliverysubsystem, 2) a microwave subsystem, 3) a vacuum subsystem, 4) a coolingsubsystem, 5) an effluent separation and disposal subsystem, and 6) adata management and safety subsystem. These subsystems are described inmore detail below. The integration of these subsystems is shownschematically on FIG. 2 . Desirable outputs from these subsystems andmethods can include a high degree of methane conversion, and a highdegree of acetylene selectivity and/or a high degree of hydrogenselectivity.

As shown schematically in FIG. 2 , a plasma-based hydrocarbon processingsystem 200 provides for the conversion of one or more inflow gases 202,204, and 208 into a mixture of gaseous products contained in an outflowstream 212 emerging from a plasma reaction chamber 214, where the plasmareaction chamber contains the plasma that has been generated by amicrowave subsystem 218. In the depicted embodiment, a hydrocarboninflow gas 202, such as methane, enters the plasma reaction chamber 214separately from the hydrogen-containing inflow gas 208 that is producedfrom a recycling of a certain fraction of the outflow stream 212. Anoptional auxiliary gas 204 such as nitrogen can be introduced separatelyas shown, or it can be mixed with one or both of the other inflow gases202 and 208. The various inflow gas streams and their direction into theplasma reaction chamber 214 are encompassed by the gas deliverysubsystem 210. The gas delivery subsystem 210 is responsible forproducing the appropriate proportions of inflow gases and controllingtheir flow rates. Once the inflow gases enter the plasma reactionchamber 214, they are energized by microwaves produced by the microwavesubsystem 218, which creates a plasma state within the plasma reactionchamber 214. An outflow stream 212 carries outflow (or “produced”) gasproducts including acetylene, hydrogen, and a mixture of unreactedmethane and higher-order hydrocarbons. Carbon solids can be entrained bythe outflow gas stream 212. An effluent separation and disposalsubsystem 220 allows for the separation of waste components from theoutflow stream 212 so that they can be disposed of, and further allowsfor the separation of desirable components into discrete streams asnecessary for further commercialization or for reintroduction into theplasma reaction chamber 214 as an inflow gas 208. For example, acetylene224 can be separated from the outflow stream 212 in theseparation/disposal subsystem 220, and it can be used commercially. Inembodiments, for example, the acetylene can be further purified for usein chemical reactions. In other embodiments, the acetylene can befurther processed, either to form other compounds or to form elementalcarbon for other uses or for disposal. In embodiments, the carbon solidsentrained by the outflow gas stream 212 can be removed by theseparation/disposal subsystem 220 as a discrete product or wastematerial 222. In the depicted embodiment, a recycled stream 228 that ispredominately hydrogen emerges from the separation/disposal subsystemand is recycled back into the plasma reaction chamber 214 as an inflowgas 208. In other embodiments, a portion or the entirety of hydrogenproduced by the reactor can be separated from the outflow stream 212 andcommercialized separately. In yet other embodiments, the separation ofoutflow stream 212 components proceeds differently: for example, carboncan be separated entirely, with a mixed hydrogen and hydrocarbon gasstream being segregated for commercialization or other uses. Theseparation/disposal subsystem can be configured to segregate singlegases or gas mixtures in accordance with specific gas processing goals.As shown schematically in FIG. 2 , a vacuum subsystem 230 surroundscertain system components to maintain them at a low pressure. A coolingsubsystem (not shown) provides appropriate cooling for each systemcomponent.

In embodiments, a number of system parameters can be modified tooptimize hydrocarbon (e.g., methane) conversion rate and acetylene orhydrogen selectivity, including input gas flow rate (SLM), inputpressure, and power per converted hydrocarbon (e.g., methane). Tables 2aand 2b show the effect of varying these parameters in several differentinstances. A useful metric for comparing results of different systemparameters is efficiency, calculated as the energy used per molecule ofmethane converted (eV/CH4). This metric is easily applied to bothindustrial uses, such as production cost per kg of product, andscientific uses, such as comparing against bond strengths andcalculating thermodynamic efficiency.

TABLE 2a 1 2 3 Reactor I.D. (mm.) 108 108 108 CH₄/H₂/N₂ Feed flow (SLM)383/460/38 367/550/37 338/676/34 Pressure (Torr) 40 42 52 eV/CH₄ 3.904.07 4.42 Effluent (SLM) 1226 1285 1353 CH₄/H₂/N₂/C₂H₂ Effluent (%)1.6/81.5/3.1/13.8 1.4/83.1/2.9/12.6 1.2/85.2/2.6/11 C₂H₂ Selectivity (%)93 93 93

TABLE 2b 1 2 3 4 5 Reactor I.D. (mm) 108 108 108 45 45 CH₄/H₂/N₂ Feedflow (SLM) 383/460/38 367/550/37 338/676/34 310/628/31 310/628/31Pressure (Torr) 40 42 52 195 254 eV/CH4 3.9 4.07 4.42 4.88 5.00 Effluent(SLM) 1226 1285 1353 1216 1206 CH₄/H₂/N₂/C₂H₂ Effluent (%) 1.6/81.5/3.1/13.8 1.4/83.1/2. 9/12.6 1.2/85.2/2. 6/11 2.6/80.4/4.8/ 11.63.0/80.2/4.8/ 11.3 C₂H₂ Selectivity 93 93 93 95 94

a. Gas Delivery Subsystem

In embodiments, a gas delivery subsystem is constructed to direct inflowgases into the plasma reaction chamber. The gas delivery subsystemcomprises two components, the delivery conduit and the gas injector.Included in the description of this subsystem are further descriptionsof (i) gases fed into the reactor (inflow gases); (ii) the deliveryconduit for conveying inflow gases into the plasma reaction chamber,where the delivery conduit includes one or more separate circuits (or“conveying circuits”) for gas flow, and where the conveying circuits caninclude a main feed gas conveying circuit, auxiliary gas conveyingcircuits for additional gases besides the main feed gas, and/or arecycled gas conveying circuit to allow return of one or more producedgases (e.g., hydrogen) to be used as inflow gases for subsequentreactions, and (iii) the gas injector assembly in fluid communicationwith the delivery conduit and its component conveying circuits thatintroduces component inflow gases into the plasma reaction chamberitself.

i. Inflow Gases

Inflow gases can comprise precursor reactant gases such as C₁-C₄ alkanehydrocarbons in various combinations. Precursor reactant gases are thosethat provide hydrogens or carbons for further reactions in the plasmastate. In embodiments, the inflow gases are methane and hydrogen, withnitrogen optionally combined with the methane. In certain embodiments,methane and hydrogen are reactants. The proportions of reactant gases,along with the optional nitrogen additive, can be varied empirically tooptimize the product profile and yield.

Inflow gases used by the plasma-based hydrocarbon processing system canbe supplied directly from feed tanks, feed lines, and/or throughrecycling. As used herein, the term “inflow gas” means any gas that isadded to plasma reaction chamber within which the plasma is formed. Aninflow gas can be a reactant gas such as methane or hydrogen, which istransformed by the plasma state into various products, as described inFIG. 1 . An inflow gas can be an auxiliary additive gas such asnitrogen. An inflow gas can be supplied from external gas sources called“feed lines,” or from intrasystem recycling, wherein a gas produced bythe system is reintroduced, in whole or in part, into the plasmareaction chamber for subsequent reactions.

An inflow gas entering the system via an external gas source or feedline can be derived from a gas reservoir such as a storage tank, or itcan be derived from an extrinsically situated flowing gas lines such asa mixed gas source line (e.g., a natural gas line or biogas line). Inembodiments, the inflow gas contains solely (or substantially only) thereactants methane and hydrogen, with no deliberately added additionalgaseous additives. The methane in the inflow gas can be obtained as acomponent of a more complex flowing gas mixture such as natural gas orbiogas. In embodiments, methane and, optionally nitrogen, are fed infrom feed lines (i.e., storage tanks or flowing gas lines), whilehydrogen can be fed in from a storage tank or it can be recycled fromthe product stream and directed back into the reactor.

A recycled gas stream used for intrasystem recycling is an effluent(i.e., outflow gas) from the plasma reaction chamber, optionallyseparated into various component gases, with some or all of this gas orthese gases reintroduced into the plasma reaction chamber. Inembodiments, the hydrogen in the outflow gas products stream isseparated from other gases and is recycled in a purified form. Inembodiments, a hydrocarbon inflow gas is introduced into the plasmareaction chamber via a flowing gas feed line, for example a natural gasline or biogas line, while hydrogen is introduced into the plasmareaction chamber separately from the hydrocarbon inflow; this hydrogencan be derived, in whole or in part, from a recycled gas stream.

In embodiments, the recycled gas can comprise a hydrogen-rich reactantgas, wherein hydrogen is the main component, with some hydrocarbons alsopresent that are capable of reactions. In embodiments, the recycled gascomprises the hydrogen-rich reactant gas, with the hydrogen-richreactant gas in the recycled gas in an amount of 80% of the recycled gasor more, or about 85% of the recycled gas or more, or about 90% of therecycled gas or more, or about 95% of the recycled gas or more. Ahydrogen-rich reactant gas can consist essentially of hydrogen, i.e.,can include about 95% hydrogen or greater, or about 96% hydrogen orgreater, or about 97% hydrogen or greater, or about 98% hydrogen orgreater, or about 99% hydrogen or greater. In embodiments, thehydrogen-rich reactant gas comprises about 90% of the recycled gas ormore, or about 91% of the recycled gas or more, or about 92% of therecycled gas or more, or about 93% of the recycled gas or more, or about94% of the recycled gas or more. In embodiments, the recycled gasconsists essentially of the hydrogen-rich reactant gas, i.e., thehydrogen-rich reactant gas comprises about 95% of the recycled gas ormore, or about 96% of the recycled gas or more, or about 97% of therecycled gas or more, or about 98% of the recycled gas or more, or about99% of the recycled gas or more. In embodiments, the recycled gascomprises a non-reactant gas such as nitrogen in addition to thehydrogen-rich reactant gas. In embodiments, the amount of hydrogen inthe recycled gas can be in an amount of 80% or greater, 85% or greater,90% or greater, or 95% or greater.

In embodiments, the remainder of the recycled gas apart from thehydrogen-rich reactant gas is nitrogen. In other embodiments, nitrogenis added as a separate auxiliary gas, apart from its presence or absencein the recycled gas. Volumes of hydrogen and nitrogen used in the systemcan be expressed in relation to the total methane flow. For example, thefollowing ratio of inflow gas feeds can be used: 1: 0-3: 0.1 methane:hydrogen: nitrogen; in other embodiments, the following ratio of inflowgas feeds can be used: 1: 1-2: 0.1 methane: hydrogen: nitrogen. Inembodiments, similar ratios of methane and hydrogen can be used in theabsence of nitrogen. In an embodiment, a methane flow into the reactorof 300-400 SLM (approximately 11-14 SCFM) can be used. In an embodiment,a methane flow of about 380 SLM (13.4 SCFM) can be used. In embodiments,these flows are suitable for a reactor power of 100kW.

In embodiments, the amount of hydrogen inflow gas can be varied in orderto select for more or less acetylene production. Increasing the amountof hydrogen entering the reactor increases the amount of this gasavailable for reacting with methane, thereby improving the conversionselectivity for acetylene production and decreasing the amount ofundesirable soot build-up. In embodiments, an increased amount ofhydrogen entering the reactor decreases the amount of ethylene in theoutflow, as compared to acetylene.

In embodiments, hydrogen is provided from hydrogen cylinders. In otherembodiments, hydrogen can be provided by recycling hydrogen that isproduced by the overall system: in other words, hydrogen produced from aC₁-C₄ hydrocarbon feedstock such as methane in the plasma reaction canbe reused as a reactant. In certain embodiments, a recycled gasconveying circuit that conveys hydrogen as an inflow gas back into thesystem can be combined with a separate inflow source of hydrogen, forexample from a hydrogen feed tank to tune the input of this gas. Thisapproach can be advantageous at certain times during the productioncycle, for example at system start-up when no recycled hydrogen has yetbeen produced, or to keep hydrogen inflow at a constant level despitevariations in hydrogen produced during recycling.

In an embodiment, the gas delivery subsystem can be precharged, forexample at system start-up, to balance the mixing of gases and toharmonize the gas flow with the microwave energy. First, the system canbe evacuated and set at a near-vacuum pressure. Second, the system canbe filled from an external source of hydrogen, either backfilled viahydrogen introduced retrograde into the recycled gas conveying circuit,or front-filled from a separate hydrogen inflow line. Third, a C₁-C₄hydrocarbon (e.g., methane) or C₁-C₄ hydrocarbon /nitrogen mixture canbe added as an inflow gas, with flows measured by flowmeters. With thesystem thus precharged with appropriate gases, the reactor can beenergized, and the inflow gases can be processed. As the inflow gasesare processed in the plasma reaction chamber, hydrogen is generated inthe outflow gas products stream, along with other gas products. Hydrogencaptured from the outflow gas products stream then can be recycled intothe system, while at the same time the exogenous hydrogen inflow isdecreased. This balancing of extrinsic and intrinsic hydrogen inflows(from external feed lines and from recycling) can facilitate a smoothstart-up procedure for the overall system.

In embodiments, methane is the main component of the hydrocarboncontaining inflow gas for the plasma-based hydrocarbon gas processingdescribed in these systems and methods. In embodiments, methane can beintroduced from gas cylinders, from pipelines, or from an inflow of amixed gas (e.g., natural gas or biogas) as described previously. A setof compressors can be used, so that methane is introduced at a correctpressure, for example at a feed pressure of at least about 2 atm. Ifnatural gas or biogas is used to provide the methane feed gas, theamount of available methane can be monitored, for example by using abenchtop gas chromatograph, and the impurities in the natural gas can beidentified and removed. For example, if the natural gas or biogas feedcontains sulfur, it can affect the purity of the acetylene productstream; such an impurity must be removed before processing. Variousimpurities that are commonly found in natural gas or biogas (e.g.,carbon dioxide, mercaptans, hydrogen sulfide, and the like) can beremoved with a series of pre-scrubbers, where the type of scrubberselected depends on the impurity to be removed.

Desirably, a mixed gas comprising methane can include a highconcentration of methane, so that it is substantially free of impuritiesor other gases. Natural gas derived directly from a natural sourcewithout commercial treatment can contain about 90% or greater ofmethane. However, natural gas that is processed to be availablecommercially, or equivalently treated biogas, can be substantially freeof non-methane gases and impurities. A hydrocarbon-containing inflow gasfrom such a source is deemed to consist essentially of methane, whichterm refers to an inflow gas containing about 95% of methane or greater.Such a gas, consisting essentially of methane, can contain, for example,about 95% methane or greater, or about 96% methane or greater, or about97% methane or greater, or about 98% methane or greater, or about 99%methane or greater. Gases provided from natural sources such as in situnatural gas (as found in wells prior to processing) or such as biogascan contain lesser amounts of methane, but they can be pretreated foruse as a hydrocarbon-containing inflow gas so that such gases havehigher concentrations of methane; in embodiments, such pretreated gasesconsist essentially of methane when used as hydrocarbon-containinginflow gases for these systems and methods.

In embodiments, other auxiliary gases can be used as components of theinflow gas stream, for example additives such as nitrogen, carbondioxide, and/or other reactive or inert gases. In an embodiment,nitrogen can be optionally used as a component of the inflow feed gas;it can also be used as a sealing gas for the vacuum pumps, as describedbelow. In an embodiment, the inflow feed gas contains about 10%nitrogen, although this amount can be varied or tuned to optimizeefficiency and selectivity for acetylene production; in otherembodiments, nitrogen can be present in amounts ranging from about 0% toabout 10%, with the nitrogen either deliberately added or extraneouslypresent, for example as a minor component adventitiously found the feedgas. In other embodiments, no additional nitrogen is included. Inaddition to its use as an inflow gas component, nitrogen in gas andliquid form can be used as a part of the cooling subsystem to coolvarious components and provide a nitrogen “buffer” around the reactor,as described below. Carbon dioxide can be included as a separatecomponent of the inflow gas, or it can be mixed into the reactoreffluent to serve as an internal standard for gas chromatographicanalysis of that effluent. In an embodiment, carbon dioxide is added tothe effluent in the amount of 30% of the methane feed in order toachieve good precision in downstream gas chromatography measurements.Other auxiliary gases can be used as inflow gases along with thereactant gases, for example helium for gas chromatography and argon.

ii. Gas Delivery Conduit

The gas delivery conduit conveys the various inflow gases (includingreactant gases, additive or auxiliary gases, and recycled gases) intothe gas injector; the gas injector delivers the various inflow gasesinto the plasma reaction chamber. The gas delivery conduit containsconveying circuits dedicated to specific gas streams: the feed gas iscarried within the feed gas conveying circuit, additional gases arecarried by one or more additional gas conveying circuits, recycledgas(es) are carried by one or more recycled gas conveying circuits. Inembodiments, these systems and methods use a hydrocarbon-bearing inflowstream as a main gas feed, for example a methane stream or a mixed gasstream (e.g., natural gas or biogas), with the main gas feed beingcarried by the feed gas conveying circuit. In embodiments, additionalgas streams can also pass through the gas delivery conduit in additionto the main gas feed, adding inert gases such as nitrogen, and/or addingreactants such as hydrogen as separate streams via their designatedconveying circuits. Furthermore, in embodiments, a recycled gas streamcan be added to the mix through a recycled gas conveying circuit, asdescribed in more detail below; a recycled gas stream can containhydrogen as the predominant component, along with nitrogen, smallquantities of other substances found in the natural gas feed, smallquantities of unreacted methane, and other hydrocarbon componentsproduced by the plasma-based hydrocarbon processing system. Inembodiments, each conveying circuit is in fluid communication with thegas injector assembly and conveys its gas separately into the gasinjector assembly, for example through a dedicated nozzle, valve, orconduit.

A schematic diagram of an embodiment of a gas delivery subsystem 300 inaccordance with these systems and methods is shown in FIG. 3 . As shownin this Figure, a hydrocarbon-bearing inflow gas stream 302 is combinedwith a hydrogen-bearing inflow gas stream 304 and an optional auxiliarygas stream 308 to enter the plasma reaction chamber 310. In the depictedembodiment, the three gas streams enter through a gas injector 312(described below in more detail) which disperses the various flows indirections and with velocities such that a vortex intermingling 314 ofthe three separate flows is produced within the plasma reaction chamber310. The intermingled gases in the vortex intermingling 314 enter areaction zone 318 of the plasma reaction chamber 310, where they areenergized by the microwave energy produced in the microwave subsystem322 to form the plasma 320 within the reaction zone 318 of the plasmareaction chamber 310. In the depicted embodiment, the inflow gases 302,304 and 308 each enter the gas injector 312 as separate streams throughseparate inlets, and each enters the plasma reaction chamber 310 throughits own outlet from the gas injector. The flow direction, flow velocityand flow rate from each outlet is oriented so that it produces thevortex intermingling 314 of the gases within the plasma reaction chamber310.

Inflow gases can be introduced into the plasma reaction chamber inconstant or variable flow patterns, and in continuous flow patterns ordiscontinuous flow patterns, and in any combination of these patterns.In embodiments, a variable flow pattern can be regular or irregular inits variability, and it can include intermittent pulses or surges offlow superimposed on an underlying wave form describing the flowpattern. A sinusoidal flow pattern would be an example of a variableflow pattern, as would a stepwise or “boxcar” flow pattern using squarewaves to delineate different amounts of flow. In embodiments, thesevariable flow patterns can include periods where there is no flow, sothat the variable flow pattern would be discontinuous. In embodiments,gases can be introduced through all of the inlets simultaneously, orgases can be introduced through different inlets at different times.Gases can be introduced at different flow rates and at different flowpatterns at each inlet. For example, a feed gas can be introducedcontinuously with a constant flow pattern, while one or more auxiliarygas streams can be introduced sporadically, i.e., discontinuously. Or,for example, the feed gas can be introduced discontinuously (i.e., withinterruptions in its inflow), with one or more auxiliary gasesintroduced variably and/or discontinuously so that the auxiliary gasesare flowing while the feed gas is not. Or, as another example, a feedgas can be introduced continuously with a continuous flow pattern, whileone or more auxiliary gas streams can be introduced continuously, butwith a different flow pattern than the feed gas. Other combinations ofcontinuous/discontinuous patterning and flow pattern variability can bearranged to accomplish specific gas processing goals, for example, todecrease soot formation in the plasma reaction chamber, or to increaseacetylene selectivity, or to allow for intermittent cleaning of thereaction tubing interior.

As previously described, gases that are energized into the plasma stateundergo a spectrum of reactions, so that a hydrocarbon feed gas istransformed into other hydrocarbons plus hydrogen. FIG. 3 shows anoutflow stream 324 emerging from the plasma 320 that contains thedesired hydrocarbon product or products, certain extraneous hydrocarbonproducts, and hydrogen gas. The components of the outflow stream 324 areseparated from each other by means of the effluent separation/disposalsystem 328, described previously.

iii. Gas Injector

The gas injector introduces the various inflow gas streams into theplasma reaction chamber through a plurality of inlets. In embodiments,the gas injector containing the flow channels for the various inflow gasstreams can be printed out of a high temperature resin. It can bedeployed within or is disposed in fluid communication with the reactorat a variable distance from the plasma reaction chamber within thereactor, where the term “plasma reaction chamber” refers to the regionwithin the reactor where the microwave energy encounters the feed gasstreams. In an embodiment, the gas injector can be positioned at theproximal end of the reactor, permitting antegrade gas flow from proximalto distal along the long axis of the reactor. In other embodiments, thegas injector can be positioned at the distal end of the reactor, or canbe positioned at any other location along the long axis of the reactor.In embodiments, the gas injector is positioned centrally within thereactor tube, with gas flow directed peripherally. In other embodiments,the gas injector is positioned peripherally within the reactor tube,with gas flow directed centrally. Gas flow exiting the nozzles can beaimed at any angle along the long axis of the tube, so that gas can flowproximally or distally in an axial direction. The nozzles can bearranged to yield symmetric or asymmetric vortex flow.

In embodiments, the inflow gas flows can be aimed by the gas injector soas to create a spiral or vortical gas flow, which assists with mixingthe various gas streams. The gas injector is configured to provide aseparate nozzle or port for each inflow gas stream as it enters thereactor. The vortical flow can be produced from a gas injector devicedisposed centrally in the reactor with two or more nozzles or ports,where each inflow gas is separately delivered through its own subset ofthe one or more nozzles or ports. In an embodiment, these nozzles orports, located centrally within the reactor, can be aimed peripherally,and can be angled to create the desired gas flow pattern. In otherembodiments, vortical flow can be produced by gases flowing into thereactor through a gas injector having two or more nozzles or portsarrayed along the periphery of the reactor, where each inflow gas isseparately delivered through its own discrete subset of the two or morenozzles or ports. In embodiments, the vortical flow serves to confinethe plasma toward the interior region of the reactor. Additional vortexflow configurations, such as reverse vortex flow, can also be employed,as would be understood by those skilled in the art.

FIGS. 4A and 4B depict an embodiment of a gas injector that iscompatible with these systems and methods. FIG. 4A shows a transversecross-section of the proximal part of the reaction chamber 402 of aplasma reactor 400, within which the gas injector 404 is centrallylocated; the approximate location of the depicted cross-section in FIG.4A is shown as Line A in FIG. 3 . The gas injector 404 shown in thisFIG. 4A encases two coaxial but separate gas flows, a central gas flow408 and a secondary gas flow 410. The central gas flow 408 contains onegas, for example the main feed gas that can contain methane, the primaryreactant. The secondary gas flow 410 contains a separate and distinctgas, for example an additional gas such as hydrogen or an auxiliary gas;this gas can also be a recycled gas such as hydrogen. Alternatively, thecentral gas flow 408 can contain the additional gas, while the secondarygas flow can contain the main feed gas. In other embodiments (notillustrated), the recycled gas flow can be maintained in a separatecoaxial chamber distinct from a flow channel for an auxiliary gas, witheach flow channel having its own set of one or more gas nozzles enteringthe plasma reaction chamber 402. For the injector design depicted inFIG. 4A, the central gas flow 408 exits the gas injector 404 centrallythrough a central gas nozzle 412 aimed distally and seen here only incross-section, while the secondary gas flow 410 exits the gas injector404 through gas nozzles 412 a and 412 b, which are aimed peripherally.As shown in this Figure, the secondary gas nozzles 412 a and 412 b aredirected at an angle that allows the secondary gas flows 414 a and 414 bto enter the plasma reaction chamber 402 to form a gas vortex within thereactor 400.

FIG. 4B shows a longitudinal section of an embodiment of a gas injector450, incorporating the principles illustrated in FIG. 4A. The gasinjector 450 depicted in FIG. 4B shows the coaxial arrangement of thecentral gas flow 452 surrounded by the secondary gas flow 454. The gasinjector 450 is positioned centrally within the reactor (not shown inthe Figure), and the gas flows from the central gas flow 452 and thesecondary gas flow 454 exit the gas injector 450 to flow into thereactor. The secondary gas nozzles 458 a and 458 b can be arranged atangles (as seen in FIG. 4A), so that the secondary gas exiting thesenozzles is aimed to create a vortex flow. As well, the gas exiting theprimary gas nozzle 460 can be directed to create or to contribute to avortex flow. In embodiments, the vortex flow created in the reactor 400by the gas injector 450 permits gas mixing, which in turn can optimizethe exposure of the gas streams to the plasma.

b. Microwave Subsystem

In embodiments, the microwave subsystem comprises the various componentsused to generate, guide, and apply microwave power to form thenon-thermal plasma that transforms the feed gas into its products.

A schematic diagram for an embodiment of a microwave subsystem is shownin FIGS. 5 and 6 below. FIG. 5 provides an overview of the subsystem’scomponents. As shown in FIG. 5 , an embodiment of the microwavesubsystem 500 includes a power supply 502, a magnetron 504, a waveguideassembly 508, and an applicator 510, with the microwave energy producedby the magnetron 504 encountering the inflow gas in a plasma reactionchamber 512 within an elongate reactor tube 514 (seen here incross-section) to create the plasma. The reactor tube 514 can be made ofquartz, as is described below in more detail. In an embodiment, thepower supply 502 requires 480 V, 150 A of AC electrical power togenerate 20 kV, 5.8 A of low ripple DC power with an efficiency of 96%to energize the magnetron. In an embodiment, the magnetron 504, alsorated at 100 kW, produces microwave power at 83-89% efficiency. Inembodiments, the microwaves produced are in the L-band, having afrequency of 915 MHz.

As shown in this Figure, the microwaves enter a waveguide assembly 508that directs them to the applicator 510, which in turn directs themicrowaves to the plasma reaction chamber 512 in the reactor tube 514.In the depicted embodiment, the waveguide assembly 508 comprises twocirculators 518 and 520, which direct the microwaves towards theapplicator 510 and which prevent reflected microwave power from couplingback into the magnetron 504 and damaging it. Each circulator 518 and 520contains a ferrite array 516 and 526 respectively that deflectsreflected microwaves in order to direct them towards the applicator 510and plasma reaction chamber 512, as described below in more detail. Eachcirculator 518 and 520 has its respective water load 522 and 524 at itsend to collect the reflected microwaves. As depicted, the secondcirculator 520 includes a power tuner 528 that steps down power using athree-stub tuner 530 in the arm that is distal to its junction with theapplicator. In the arm of the second circulator 520 that interfaces withthe applicator 510, a three-stub tuner 532 is arranged distal to thedual-directional coupler 534; this arrangement is intended to minimizemicrowave reflection and optimize the microwave energy directed into theapplicator 510. A quartz window 538 is inserted between the secondcirculator 520 and the applicator 510 to prevent arcing. When the plasmais off and the microwaves are on, a standing wave is set up in theapplicator 510 between the three-stub tuner 532 and a sliding shortingplate 540 on the end of the applicator 510 such that the electric fieldis sufficient to initiate breakdown of the feed gases in the reactortube 514 that contains the plasma reaction chamber 512. The reactor tube514 runs through the broad wall of the applicator 510 but is not indirect contact with the microwave waveguide 508. Once the initiation ofthe plasma state is achieved, the three-stub tuner 532 can then beadjusted to match the impedance of the incoming microwave signal to theplasma-loaded applicator 510. Microwave energy entering the applicator510 is tuned to peak at the center of the plasma reaction chamber 512,using the shorting plate 540 as needed to change the dimensions of thecavity within which the plasma is formed.

To optimize the power for producing the plasma, it is desirable to matchthe impedance of the waveguide 508 to the impedance of the applicator510 in the presence and the absence of the plasma. Plasma impedance isdynamic however, and can change based on the operating pressures, gasflows, and gas compositions in the plasma reaction chamber 512. Inembodiments, the microwave subsystem can be equipped with a standardthree-stub autotuner 532, which has three metal stubs inserted into thewaveguide. The depth to which each of these stubs is inserted into thewaveguide alters the phase of the microwaves entering the reactor 510and allows for power matching into the plasma. Microwave power and phasemeasurement in the autotuner 532 allow the autotuner 532 to modify stubdepth algorithmically, so that reflected power (i.e., the power notabsorbed by the plasma), is minimized. In embodiments, a dualdirectional coupler 534 with attached power diodes (not labeled) can beincluded, to measure forward and reflected power in the subsystem. Thecoupler 534 can be fitted with two small holes that couple microwaveswith a known attenuation to the diodes, which convert the microwave intoa voltage. In embodiments, reflected power is less than 1% of totalmicrowave power sent into the system. In embodiments, the microwaveapplicator 510 is a single-mode resonant cavity that couples themicrowaves to the flowing gas feed in the plasma reaction chamber 512. Asliding electrical short 540 can be built into the applicator 510 tochange total cavity length. In embodiments, the plasma for the 100-kWdemo unit can generate upwards of 10 kW of heat, which can be removedvia water and gas cooling subsystems.

The plasma is created in the plasma reaction chamber 512 within theelongate reactor tube 514. In embodiments, the reactor tube 514 cancomprise a long aspect ratio fused quartz tube, with an outer diameter,between about 30 and about 120 mm, a length of approximately 6 ft, and athickness varying from about 2.5-6.0 mm. In an embodiment, the reactortube can have an outer diameter of 50 mm, or an outer diameter of 38 mm.In embodiments, tube sizes can have an outer diameter (OD) andcorresponding inner diameter (ID) of 120/114 mm OD/ID, or 120/108 mmOD/ID, or 80/75 mm OD/ID, or 50/46 mm OD/ID, or 38/35 mm OD/ID. Inembodiments, the reactor tube 514 has a consistent diameter throughoutits length. In other embodiments, the reactor tube 514 can have avarying diameter, with certain portions of the tube 514 having a smallerdiameter, and other areas having a larger diameter. In embodiments, atube can have an outer diameter of about 50 mm at the top and about 65mm at the bottom. In embodiments, the tube can have a narrower diameterat a preselected portion of the tube, for example, approximately in themiddle of the tube. Quartz is advantageous as a reactor tube 514material because it has high temperature handling, thermal shockresistance, and low microwave absorption.

FIG. 6 shows, in more detail, a microwave subsystem 600, such as wasdepicted in FIG. 5 , and the paths of microwave energy 605, 607, and 615flowing therein; in FIG. 6 , certain features of the microwave subsystem600 are shown schematically but, for clarity, were not labeled as theywere in FIG. 5 . As shown in the embodiment depicted in FIG. 6 ,microwave energy, generated by the magnetron 604, is directed forwardalong a forward energy path 605 from the magnetron 604 to the distal endof the waveguide assembly 608, from which it is reflected along anantegrade (forward) reflected path 607. The direction of the antegrade(forward) reflected path 607 is shaped by its encounter with the ferritearray 626 in the second circulator 620, which deflects the reflectedmicrowaves 607 towards the applicator 610 and the plasma reactionchamber 612. Microwaves can also be reflected retrograde from theapplicator 610 along a retrograde (reverse) reflected path 615, whichpasses backwards through the second circulator 620 into the firstcirculator 618, where the microwaves in this path 615 are collected bythe water load 622 within the first circulator 618. The retrograde(reverse) reflected path 615 is deflected by the ferrite array 626 inthe second circulator 620, and then by the ferrite array 616 in thefirst circulator 618 to establish its final direction. In an embodiment,forward power in the system is approximately 25 kW, with reflected power1% of this or less, with the goal of 0% reflected microwave energy. Inembodiments, the forward power in the system is approximately 30 kW; inother embodiments, the forward power in the system is approximately 100kW. In yet other embodiments, forward power levels of about 8 kW, about10 kW, or about 19-20 kW can be employed. In embodiments, the system canadvantageously encompass a forward power at levels less than about 100kW.

In an embodiment, the microwave subsystem includes a single arm pathwaytowards the plasma reaction chamber, as depicted in FIG. 5 and FIG. 6 .In other embodiments, a double-arm applicator pathway can be employed,as shown below in FIG. 7 . As shown schematically in FIG. 7 , adouble-armed microwave subsystem 700 comprises a magnetron 704 producingmicrowave energy that enters the circulator assembly 703, whichcomprises two circulators, labeled “1” and “2.” Microwave energy passesthrough the circulators substantially as depicted in FIG. 6 , to enter apower splitter 706 that directs the microwaves into two waveguide arms709 a and 709 b, within which arms the microwaves are aimed towardstheir respective applicators 710 a and 710 b. In embodiments, thedouble-arm waveguide 709 a and 709 b plus applicators 710 a and 710 bcan split the incident power in a 50:50 ratio, but in other embodiments,a selected ratio of power splitting can be engineered.

Certain maintenance measures within the microwave subsystem can extendthe lifespan of the components and optimize the product output. Inembodiments, for example, the reactor can be cleaned periodically. It isunderstood that carbon soot build-up can occur in the reactor tube whennon-thermal plasma technology is used to convert methane to acetylene,and the presence of soot can lead to localized areas of overheating onthe quartz surface with subsequent damage to the reactor tube. Inaddition, soot that accumulates distal to the microwave coupling canbecome conductive, leading to formation of undesirable arcs. Therefore,in embodiments, regular cleaning of the reactor is undertaken in orderto minimize these problems. Cleaning can be undertaken on a periodicbasis, or based on the discontinuous demands for commercial operation,or in response to observable characteristics of the plasma or effluent.For cleaning purposes, several steps are typically employed: 1)de-energizing the plasma process with in the plasma reaction chamber,either by switching off the microwave power creating the plasma, or byshifting the gas inflow from the process gas to an inert cleaning gas orgas mixture (e.g., pure N₂ or a combination of nitrogen with air or withother cleaning gases), or both; 2) discontinuing the feed gas inflow andintroducing an inert gas mixture (e.g., nitrogen) that purges the inflowlines of the flammable feed gas; 3) filling the reactor with thecleaning gas (e.g., nitrogen mixed with air); 4) reenergizing the plasmareaction chamber with microwave energy to create a plasma state from thecleaning gas, including monitoring and adjusting the microwave energyand the pressure to permit effective cleaning; 5) reversing the processonce the reactor tube is clean, with evacuation of the cleaning gas ordisplacement of the cleaning gas by the feed gas, leading to filling thereactor tube with the feed gas, and subsequent energizing of the feedgas to form a plasma.

In embodiments, soot deposition (and therefore the need for cleaning)can be minimized by increasing the hydrogen component of the inflowgases; this approach, however, has the drawback of decreased efficiencyin hydrocarbon (e.g., methane) conversion. In other embodiments, sootdeposition can be managed directly by periodic manual cleaning; thisapproach has the drawback of requiring physical interventions to accessthe internal surfaces of the reactor tubing where the soot accumulates.In yet other embodiments, soot deposition can be managed by periodicallychanging the gas inflow into the plasma reaction chamber from thehydrocarbon : hydrogen feedstock used to produce acetylene to a hydrogen: nitrogen mix which, at low power, forms a plasma that removes sootthat has been deposited on the inner surface of the reactor tube. In anembodiment, a pure CO2 plasma can be used as a cleaning plasma. In anembodiment, a hydrogen: nitrogen gas mixture can be used, with a H: Nratio of 5-15: 1 can be used, at a power of about 8 kW. In anembodiment, this gas-based cleaning protocol can be carried out on aperiodic basis (for example, with a cleaning run of 1-2 minutes everyhour or two), aiming for a 1-2% downtime for cleaning out of thecontinuous run scheme. In other embodiments, a nitrogen: air mixture ata 50:4 ratio can be used, resulting in a cleaning time of about threeminutes every 2-3 hours.

An embodiment of this system contains parallel microwave reactor setupsmultiplexed together, with a first reactor and a second reactor joinedafter the reactor tube and heat exchanger and isolation valves for eachreactor but sharing vacuum pumps. A first reactor’s magnetron can beshut off and, and the reactor isolated by the isolation valve, thenopened to an alternate vacuum system, while the second reactor isoperating to energize the feedstock gas in its plasma reaction chamber.A cleaning plasma can then be utilized for the first reactor. Once thecleaning is done, the first reactor system will be evacuated of thecleaning gas mixture and purged with nitrogen, then purged again by therespective mixture of new feed gas and recycled gas used for theprocess, then reopened to the main vacuum system and reignited. Thesecond reactor can be cleaned in turn, using the same sequence. In someembodiments, the total number of parallel reactors can be increased toinclude three or more reactors, with their cleaning cycles sequencedsuch that the total throughput of the multiplexed system is constantwhile any one reactor is undergoing cleaning. This cleaning step cantherefore be cycled through the multiplexed reactor system individuallyor in small groups indefinitely, with cycles timed such that there is noloss in product throughput over continuous use.

c. Vacuum Subsystem

In embodiments, a vacuum system is arranged around all componentsbetween the gas injector providing gas inflow to the reactor and theproduct outflow stream distal to the reactor. Maintaining a low pressurein the system contributes to its efficiency (where efficiency ismeasured by eV of energy per mol of methane converted to acetylene). Inembodiments, a vacuum is maintained in the reactor, or a low pressureenvironment is produced, on the order of about 30 to about 120 Torr, or60 to about 100 Torr, or 70 to about 80 Torr. In embodiments, a lowpressure environment on the order of about 120 to about 280 Torr, orabout 150 to about 200 Torr, or about 170 Torr. In an embodiment, anoperating pressure of about 70 Torr is maintained for all hydrocarbonfeed gases except ethane, which is processed at an operating pressure ofabout 120 Torr.

A simplified schematic of a plasma-based hydrocarbon processing system800 highlighting the vacuum subsystem 802 a and 802 b is shown in theFIG. 8 , with arrows indicating the direction of gaseous flow throughoutthe system 800. The vacuum subsystem 802 a and 802 b envelopes certaincomponents of the processing system 800 to maintain a pressure in thosecomponents in the range of about 30 to about 120 Torr. Alternately, thesame system can maintain a pressure in those components in the range ofabout 120 to about 280 Torr, or about 150 to about 200 Torr, or about170 Torr. As depicted in FIG. 8 , the vacuum subsystem designated by thedashed line 802 a creates a first reduced-pressure environment aroundthe reactor 810 and its outflow stream 816, and around variouscomponents downstream from the reactor 810, all as described in moredetail below; the vacuum subsystem designated by the dashed line 802 bcreates a second reduced pressure environment around the gas deliverysubsystem 804. For purposes of clarity, a portion of the vacuumsubsystem is identified by dashed line 802 a and a portion of the vacuumsubsystem is identified by dashed line 802 b; these two dashed lines canrepresent separate subsystems, or they can be merged together torepresent a single vacuum subsystem. Subsystems and components shown inthis Figure for clarity include: (i) the gas delivery subsystem 804 thatpasses the inflow gases, including hydrocarbon feed gas 806 andhydrogen-containing recycled gas 812, through their respective feed gasinlets (not shown) into the reactor 810; (ii) a microwave deliverysystem 808 a that forms the microwaves 808 b that act upon the inflowgases (i.e., the hydrocarbon feed gas 806 and the hydrogen-bearingrecycled gas 812) in the reactor 810 to effect chemical transformationsin the two inflow gases 806 and 812 in the plasma reaction chamber 811region of the reactor 810, with the products of these chemicaltransformations exiting the reactor 810 as the outflow stream 816; (iii)an effluent separation and disposal system comprising an acetyleneseparator 814 and a hydrogen separator 818 that separates the outflowstream 816 into its gaseous components, with the remainder of theoutflow stream 816 distal to the acetylene separator 814 and thehydrogen separator 818 becomes the recycled gas stream 812. As mentionedpreviously and as shown in this Figure, certain components situateddownstream from the reactor 810 are also contained within the vacuumsubsystem as designated by dashed line 802 a, such as a filter 820 forthe outflow stream 816, a heat exchanger/separator 822, and a series ofpumps 824 and 828. In this Figure, a cold trap 830 for removing higherorder hydrocarbons is situated outside the vacuum subsystem asdesignated by dashed line 802 a, as are the acetylene separator 814 andthe hydrogen separator 818.

The filter 820 shown in the Figure is intended to remove carbon solidsfrom the outflow stream 816. In embodiments, the plasma process makes asmall amount of carbon solids as a by-product; for example, carbonsolids can be produced in the range of 0.1-0.5%. Therefore, it isdesirable to filter the outflow stream 816 to remove these carbon solidsin order to prevent these particles from fouling the downstreamcomponents of the system. Since the filter 820 is the first surface thatthe outflow stream 816 encounters after leaving the reactor 810, the gasin this stream is very hot (on the order of 400 - 1000° C.). Therefore,the material for the filter 820 is selected so that it can withstandsuch temperatures, with or without additional cooling. In embodiments,the filter 820 can be made of ceramic materials or of stainless steel,with cooling added as needed.

d. Cooling Subsystem

In embodiments, a cooling subsystem can be implemented to control theoperating temperatures for the various components of the gas processingsystem described herein. In embodiments, the plasma formed in thereactor reaches a temperature between 2000 - 3000 K (1700 - 2700° C.),exiting the reactor at a temperature of about 400 - 1100° C. To protectthe downstream components of the system from heat damage, cooling isprovided. In addition, it is desirable to cool the reactor itself, forexample to keep the outer temperature of the reactor tube below 500° C.Moreover, the reactor tube is more likely to retain heat duringgas-based cleaning (as described above) vs during acetylene production,so that more cooling power can be required intermittently to protect thereactor tube from heat stress. In embodiments, the cooling for thesystem includes two types of cooling: water cooling and gas cooling.Water cooling can be used for many of the components of the system, forexample the magnetron, the power supply, the vacuum pumps, theapplicator, and the like. Gas cooling can be employed for othercomponents as appropriate, for example, the reactor tube, the reactoritself, and the various O-ring seals in the system. In embodiments,nitrogen is used for gas cooling. Nitrogen has the additional benefit ofreplacing atmospheric gases in enclosed parts of the system, thusenhancing safety. In an embodiment, the reactor tube and the applicatorcan be enclosed in a sealed, nitrogen-purged (oxygen-free) environment,where the presence of nitrogen provides cooling and also serves as asafety mechanism: by replacing the oxygen in the environment around thereactor system, the nitrogen gas coolant reduces the chance of explosionif a leak is created.

e. Effluent Separation and Disposal Subsystem

In embodiments, the outflow stream emerges from the low-pressureenvironment created by the vacuum subsystem, and then undergoes furthermanagement to separate the desired gaseous products from each other andfrom the waste products. Methane and other hydrocarbon-containing gasessuch as ethane, propane, butane and the like produce acetylene andhydrogen when energized in a non-thermal plasma as described herein,along with particulate carbon and higher-order hydrocarbons. To optimizethe economics of the process and to provide a customized gas flow forrecycling, a set of components is positioned distal to the vacuumsubsystem to segregate certain of the gaseous components in the outflowstream from each other.

In embodiments, it is envisioned that a plasma-based hydrocarbonprocessing system and the methods of its use described herein convertmethane in a stoichiometry that is net hydrogen positive, with 1.5 molesof hydrogen being generated for every mole of methane consumed. Theoutflow stream thus contains a mixture of hydrocarbons, including thedesirable product acetylene, along with a predominance of hydrogen. Inembodiments, this hydrogen can be separated from the outflow stream, forexample by using a membrane separator to separate the hydrogen from theremainder of the effluent. After separation, hydrogen can be purifiedand commercialized as a separate gas product; alternatively, or inaddition, hydrogen can be, in whole or in part, recycled into thesystem, as illustrated in previous Figures. In other embodiments,acetylene can be separated from the outflow stream instead of or inaddition to hydrogen separation. For example, acetylene can be absorbedin an absorption column and then desorbed and collected. In anembodiment, the outflow stream from the reactor can first be treated toremove particulate carbon and condensates, and then acetylene can beremoved. After the acetylene is removed, the hydrogen can be optionallyremoved, captured, or recycled.

As the outflow stream leaves the plasma reaction chamber, it contains acombination of gases, volatilized higher-order hydrocarbons, andparticulate carbon. As previously described, the particulate carbon canbe filtered out immediately downstream from the reactor chamber. Inembodiments, the outflow stream can subsequently be passed through acold trap in order to remove certain higher-order hydrocarbons from theoutflow stream as condensates. After passing through the cold trap, theoutflow stream can be further separated. For example, other higher-orderhydrocarbons can be removed from the outflow stream as described below.These compounds are typically deemed waste products, and they can bediscarded or disposed of after their removal. Following orsimultaneously with the removal of higher-order hydrocarbons, acetyleneand hydrogen are separated from the outflow stream via the effluentseparation and disposal subsystem. The separation process proceeds usingone or more separation technologies, such as adsorption technologies,absorption technologies, chemical reaction technologies such asoxidization or catalyst-mediated conversion, and the like.

i. Adsorption

In certain embodiments, for example, the outflow stream can be passedthrough an adsorption column, where the column contains a highsurface-area adsorbent material that can selectively remove acetylene orhigher-order hydrocarbons from the outflow stream flowing therethrough.In embodiments, adsorbent material can include appropriately sizedmaterials such as activated carbon, zeolites, silica aerogels, molecularsieves, metal-organic frameworks (MOFs), coordination polymers, clays,diatomaceous earth, or pumice. The adsorbent material can be a powder ora film, or it can be formed into spherical pellets, rods, or othershapes which may be useful. These adsorbent materials can be modified bycalcination at elevated temperatures, ion-exchange, or doping withmolecules that increase adsorption affinity or capacity. Additionally, acombination of two or more adsorbent materials can be used to takeadvantage of multiple physical properties. The adsorbent materials canbe contained within a single adsorbent column or divided into multipleadsorbent columns to trap different impurities from the outflow streamin distinct locations. Advantageously, adsorbent materials can beselected to minimize product loss as the outflow stream passes throughthe adsorbent column: in some instances, higher-order hydrocarbonimpurities have a higher affinity for the adsorbent material than doesthe desired product; in other instances, the impurities can displace theproduct molecules off the surface of the adsorbent. In either case,product loss is minimal.

Under certain circumstances, adsorbents can be disposed of after asingle use if the capacity of the adsorbent and the concentration ofimpurities allows for sufficient impurities to be removed beforedisposal. Under other circumstances, for example if disposal isunfeasible for economic or logistical reasons, the adsorbent can beregenerated and re-used cyclically. Methods for regenerating theadsorbent include pressure reduction, solvent washing, heating, anddisplacement by another gas. During regeneration, the impurities can bedesorbed off the surface of the adsorbent, or they can be convertedin-situ to another chemical that is easier to desorb. If the impuritieshave been converted to an acceptable derivative molecule, this moleculecan be desorbed in-line and released into the process stream. If theimpurities are unaltered on the surface of the adsorbent, so that theycannot be released into the downstream flow, they can be diverted to aside stream to be vented, incinerated or collected for waste disposal.In embodiments, an automated system can arrange for alternation betweenor among multiple adsorber vessels, allowing for regeneration cycles ina continuous operation; such a system has been referred to in the art asa swing adsorber.

Adsorbers can be used for further separation of the outflow stream afterthe removal of higher-order hydrocarbons. Depending on the preferredmode of adsorption and desorption, a pressure swing adsorber (PSA), avacuum swing adsorber (VSA), or a temperature swing adsorber (TSA) canbe used. For example, in certain embodiments, the outflow stream can befed into a PSA system in order to separate hydrogen gas from the outflowstream. In the PSA system, the outflow stream is pressurized and fedinto an adsorption column in which all non-hydrogen components areadsorbed onto the adsorbent material. With all non-hydrogen materialsremoved from the stream a purified hydrogen exits the column. Inembodiments, the feed for the PSA system can be the outflow stream fromthe plasma reactor, or it can be the collected gas from the firstabsorption column described above, or some combination thereof.

Or, for example, the outflow stream can be fed into a TSA system that isadapted for separating higher acetylenes from the outflow stream. Asused herein, the term “higher acetylenes” refers at least to alkynescontaining 3 and 4 carbon atoms, although it can also be applied to allgaseous alkynes and to gaseous aromatics. Through use of a TSA system,higher acetylenes can be separated significantly, even completely, froman acetylene stream without acetylene loss. In embodiments, the higheracetylene molecules can displace acetylene on the surface of anadsorbent, allowing for extreme selectivity in separating the higheracetylenes from the acetylene stream. In order to accomplish this, theadsorption process advantageously is terminated before the higheracetylenes are themselves displaced by an even heavier molecule likebenzene. Therefore, the adsorption cycle in the TSA should be tuned toallow the higher acetylenes to be adsorbed and retained on the adsorbentsurface, but to prevent the higher acetylenes from being displaced.Thus, before the higher acetylenes are displaced off the adsorbentsurface, the reactor is closed off to the process stream. The adsorbentcan then be disposed of and replaced, or alternatively, regenerated. Inregeneration, the outflow stream is diverted from the adsorber, and hotair (for example, >300° C. or >350° C.) is passed over the adsorbentbed. Alternatively, the regeneration can be conducted with hot nitrogenor some mixture of air and nitrogen. In embodiments, the gas temperaturecan be between 120° C. and 350° C. The regeneration gas mixture and thetemperature can be varied over the course of the regeneration.Regeneration can also be performed while the adsorber bed is beingactively cooled either in certain sections or in its entirety. Thelocations and amount of optional cooling can also be varied over thecourse of regeneration. The impurities are released from the adsorbentand either vented or burned. In some iterations, multiple vessels can beused for a continuous operation in which some vessels are adsorbingwhile others are regenerating.

Adsorber vessels can be covered in an insulating material to maintain anelevated temperature during either operations and/or regeneration. Theadsorber design can include many aspects known by those of ordinaryskill in the art. For controlling the process and regeneration gasflows, internals devices such as spreaders, distributors, tubes,channels, plates, screens, and the like can be used. Additionalinternals devices can be used to control the adsorbents locations and/orperformance, such as screens, supports, and other packing materials.Additionally, internal objects to improve heat transfer can be used,including materials with higher heat conductivity in a variety ofphysical shapes, such as rods, tubes, wires, balls, and the like. Inembodiments, the amount of filler materials can be anywhere from 0 to50% of the adsorber volume. Further, adsorbers can include designsand/or systems to actively cool the bed, e.g., tube and shell designs.

In another embodiment, the TSA can be modified to remove carbon dioxideand hydrogen sulfide in addition to higher acetylenes. By operating theTSA under pressure, the adsorbent can simultaneously remove carbondioxide, hydrogen sulfide, higher acetylenes and aromatic mixtures(e.g., mixtures of benzene, toluene, and xylene isomers, collectivelyreferred to as BTX). This can be achieved by operating the TSA atpressures higher than 5 barg. Other arrangements allowing selectiveremoval of impurities would be readily envisioned by skilled artisans.For example, certain impurities such as CO₂ and/or BTX can be removed bya dedicated removal system before the gas stream is directed to the TSA,with the TSA’s operating parameters being tuned to remove the residualimpurities. Impurities in the gas stream such as alcohols (methanol,ethanol, butanol, and the like), sulfides and mercaptans, acetones andother small ketones, water, ammonia, carbon monoxide and carbon dioxide,oxygen, and the like, can be removed by the temperature swing adsorptionprocess with the adjustment of the TSA parameters and/or with theaddition of pressure.

In certain embodiments, the adsorption process can be modified so thatacetylene and hydrogen can be separated through the temperature swingadsorption mechanism by modifying the timing of the temperature swingadsorption process or by modifying the amount of adsorbent in the TSA.In embodiments, compared to the adsorption period for a similarly sizedadsorber that separates acetylene from higher acetylenes, the adsorptionperiod for separating hydrogen and acetylene is shorter, and may betermed “short-cycle temperature swing adsorption.” By exposing the gasstream to temperature swing adsorption during this abbreviated amount ofthe entire TSA cycle, the short-cycle temperature swing adsorptionprocess separates hydrogen from a mixture of acetylene and higheracetylenes. Short-cycle temperature swing adsorption is, accordingly,especially advantageous if its product, a mixture of acetylene andhigher acetylenes, is desirable. The cycling for short-cycle temperatureswing adsorption can be understood in more detail as follows: if thelength of the entire temperature swing adsorption cycle (from initiationof adsorption to commencement of adsorber regeneration) is T_(x), alimited period of time at the beginning of the adsorption cycle T₁ canbe dedicated to separating acetylene and its entrained higher acetylenesfrom the hydrogen stream, with the TSA remaining offline during theremainder of the adsorption cycle T₂, where T₂ = T_(x) - T₁. Thisadjusted adsorption schedule for short-cycle temperature swingadsorption employs the first portion of the overall adsorption cycle T₁for separating acetylene and entrained higher acetylenes from hydrogen,with T₁ ranging in length to occupy the first 10% to 25% of the entirecycle T_(x). To employ short-cycle temperature swing adsorption, a TSAsystem as described above is operated for the first part of its cycle T₁to remove the acetylene and higher acetylenes from the gas stream,allowing hydrogen to pass through. The TSA system is then offline duringthe remainder of its cycle, T₂. Regenerating the TSA adsorbent at theend of T₂ will prepare the TSA for another separation cycle.

While the TSA can be used for either a short cycle or a regular cycle oftemperature swing adsorption following its regeneration at the end ofT₂, an alternation of short-cycle and regular cycle temperature swingadsorption using the same TSA device may not be advantageous. Instead, asingle TSA device can be dedicated to the short-cycle process; in such adedicated device, regenerating the TSA adsorbent at the end of T₂prepares the device for another cycle of separating acetylene and higheracetylenes from hydrogen, i.e., short-cycle temperature swingadsorption. The short-cycle temperature swing adsorption process allowsacetylene and admixed higher acetylenes to be removed from the gasstream while the hydrogen passes through the TSA, following whichhydrogen and acetylene mixture can be processed separately after theirpassage through the TSA device. As an alternative to varying theduration of the adsorption cycle, as described above, a comparableseparation can be achieved by increasing the amount of adsorbent in theTSA device without changing the time frame for exposure to the gasstream, or in concert with changing the time frame for exposure to thegas stream.

As mentioned above, short-cycle temperature swing adsorption separatesacetylene, along with higher acetylenes that accompany the acetylenes,from the incoming gas stream. The product produced by short-cycletemperature swing adsorption is thus acetylene in combination with thehigher acetylenes. In contrast, the standard TSA separates higheracetylenes from the gas stream, leaving behind a mix of hydrogen andacetylene that will need to be further separated into a hydrogenfraction and a purified acetylene fraction. In contrast to the shortcycle temperature swing adsorption process, the standard cycle TSA isoffline during the initial part (T₁) of the cycle having a time durationT_(x), and operates during the latter part of the cycle T₂; the regularcycle TSA is online during a period that corresponds approximately tothe time that the short cycle TSA would be offline. As with theshort-cycle TSA, the standard-cycle temperature swing adsorber wouldcommence adsorbent regeneration at the end of the cycle time T_(x), butin contrast to the short-cycle TSA, the standard cycle TSA would remainoffline during the first quarter of the cycle (Ti).

For certain uses, the separation of acetylene and higher acetylenes fromthe residual hydrogen, as carried out by the short-cycle TSA step,yields a commercially acceptable output product. For example, in torchapplications, as described in more detail below, it can be acceptable toinclude the higher acetylenes in the acetylene output product, and thesimple separation of the acetylene/higher acetylene mix from residualhydrogen is commercially acceptable. In such applications, a short-cycleTSA can be used as a single stage to separateacetylene-plus-higher-acetylenes output product from the residualhydrogen stream. For other uses, a substantially pure acetylene productis desirable, wherein the higher acetylenes have been removed from theacetylene output product. For these purposes, and the use of theshort-cycle temperature swing adsorption can be combined with astandard-cycle temperature swing adsorption in a multistep process. Forexample, standard-cycle temperature swing adsorption can remove thehigher acetylenes from the gas stream as it passes through a first TSA,and then the outflow from the first TSA (such outflow still a mixture ofhydrogen and acetylene but with higher acetylenes removed) can bedirected into a second TSA that uses short-cycle temperature swingadsorption to separate the purified acetylene from the gas stream,allowing the hydrogen to pass through. While other separation mechanisms(absorption, membranes, etc.), can be used with the short-cycle TSA toremove higher acetylenes from the short-cycle adsorption product, theuse of the short-cycle TSA in combination with the standard-cycle TSAcan offer an advantageous alternative to using the standard-cycle TSA incombination with membrane-based separation technologies that requirepressurizing the gas flow to pass through membranes to effectacetylene/hydrogen separation. In other embodiments, a TSA such as astandard TSA or a short-cycle TSA can be implemented in keeping with thefollowing parameters. In a TSA system with a given adsorbent, volume,temperature, pressure, flow rate, influent composition, and othercharacteristics that are constant or are given functions of time, theperiod of time for capturing a specific gas A by the TSA can be termedT_(c)(A), or the “capture period” for Gas A. In other words, T_(c) (A)(the capture period for Gas A) is the time between the moment the bed isbrought online to the moment just before gas species A reaches anunacceptable concentration in the outflow gas stream. In a short-cycleTSA that is designed to capture acetylene, for example, the captureperiod of acetylene would be T_(c) (acetylene) or T_(c) (C₂H₂). For astandard TSA, the first species to be captured is the higher acetylenespecies, Gas B, that is first to appear in the outflow gas stream; itscapture period is termed T_(c) (B). For the standard TSA, the bed mustbe taken offline and replaced or regenerated after T_(c) (B). Similarly,for the short-cycle TSA designed to separate acetylene from theremainder of the gas stream, it must be taken offline and regenerated orreplaced after T_(c) (C₂H₂).

In cases where it is advantageous to have a standard TSA in seriesbefore a short-cycle TSA, it may also be advantageous to design theadsorbent beds for each device such that T_(c) (B) for the standard TSAis equal in duration to T_(c) (C₂H₂) for the short-cycle TSA. When theadsorbent beds are designed at these aligned scales, the short-cycle TSAcan be exposed to a consistent amount of acetylene in each cycle.

In embodiments, the cycle timing for the standard TSA in series before ashort-cycle TSA can be arranged as follows. For the standard TSA, theacetylene is being captured throughout T_(c) (C₂H₂). Then, throughT_(r), the period after the conclusion of T_(c) (C₂H₂) but before theconclusion of T_(c) (B), the acetylene is being desorbed from thestandard TSA as it is displaced by higher acetylenes which continue tobe adsorbed. During T_(c) (C₂H₂) therefore, the gas that exits thestandard TSA is devoid of both acetylene and higher acetylenes. DuringT_(r), the gas that passes through the standard TSA is enriched inacetylene but still devoid of higher acetylenes. During this time periodT_(r), the amount of acetylene in the outflow stream from the standardTSA is greater than the amount entering the standard TSA because theacetylene being replaced by higher acetylenes on the standard TSAadsorbent bed is being added to the outflow stream. The total amount ofacetylene that flows to into the standard TSA adsorption bed over T_(c)(B) flows out through the standard TSA outflow stream over the shorterduration T_(r). The short-cycle TSA therefore is not adsorbing acetyleneduring the standard TSA’s T_(c) (C₂H₂), because the acetylene is beingadsorbed by the standard TSA. During T_(r), the acetylene exiting thestandard TSA reaches and is adsorbed onto the short-cycle TSA. If theshort-cycle TSA has been sized properly to have an acetylene saturationtime that meets or exceeds T_(c)(B), the standard TSA’s higher acetylenecapture period, the gas that passes out of the short-cycle TSA will bedevoid of both acetylene and higher acetylenes for the entirety of itsactive period, that is, the standard TSA’s T_(c) (B). At the end of thisactive period, both vessels can be taken offline and replaced by freshvessels and/or regenerated.

In certain embodiments, the stream being processed in a standard orshort-cycle TSA may contain a wide variety of products that have weakaffinity for the adsorption medium and as such pass readily through tothe outflow gas along with the hydrogen. Such weak-affinity gases thatmay be present in the hydrogen-rich outflow gas include methane,nitrogen, carbon dioxide, and low mass alkane and alkene species. Insuch cases, the standard TSA will separate higher acetylenes from anoutflow gas mixture of acetylene and gases with weak affinity for theadsorbent, and the short-cycle TSA will separate acetylene and higheracetylenes from gases with weak affinity. As a general set ofprinciples, the standard TSA can be used if the desired outflow gas isto comprise a mixture of acetylene and gases with a weak affinity forthe adsorbent, while the short-cycle TSA can be used if the desiredoutflow gas is only to comprise gases with weak affinity for theadsorbent. In order to separate acetylene from higher acetylenes andfrom gases having a weak affinity for the adsorbent, the standard TSAcan be used in combination with the short-cycle TSA, for example withthe two in series, standard TSA followed by short-cycle TSA.

A variety of adsorption strategies can be implemented to separateacetylene with the ideal mixture of impurities for hydrogen andacetylene black production, torch gas production, or another applicationthat tolerates or demands an impure stream. These strategies can includethe partitioning and recombination of gas streams desorbed from orpassing through one or more separation modules.

Partitioning, for example, can be done based on gas flow, adsorbenttemperature or pressure, or time online. The composition of the gascaptured by the adsorbent is variable based on the temperature,pressure, the period the bed is on-line, the type of adsorbent, andother factors. During regeneration, therefore, the composition of thegas stream released from the adsorbent bed changes as it is heated ordepressurized over time. The composition of the released gas can befurther controlled by splitting the gas based on the temperature andpressure of the adsorbent when the gas was released.

To accomplish gas separation using this technique, a TSA bed beingregenerated is heated over time. The adsorbent bed first releases ahydrogen-rich gas mixture near the starting temperature. Next, nearlypure acetylene is desorbed at moderate temperatures. As the temperaturerises further, a mixture of acetylene and higher acetylenes is releasedfrom the adsorbent. Finally, heavier compounds remain and must beliberated with the help of hot air as a regeneration gas. This TSA bedhas the first portion of released gas (i.e., the hydrogen-rich gasmixture) directed to the active TSA bed to be reprocessed. The secondportion of released gas, pure acetylene, can be used as feedstock forchemical processes and the like, as described below in more detail. Thethird portion, comprising acetylene and higher acetylenes, can bedirected to a reactor for conversion into hydrogen and acetylene black,as described below in more detail. The fourth portion, comprisingheavier compounds, can be removed with air and vented, restoring theadsorbent to its initial state.

ii. Absorption

In certain embodiments, the outflow stream can be passed through anabsorption column, wherein a solvent at an optimized flow rate runningcounter-current to the outflow stream preferentially absorbshigher-order hydrocarbons from the flowing outflow stream instead ofabsorbing the desired gas product like acetylene. The higher-orderhydrocarbons can then be separated from the solvent in a second column,and the solvent is returned to the absorption column. Examples ofsolvents with stronger affinity for higher-order hydrocarbons over thedesired gas product include methanol, ammonia, toluene, benzene,kerosene, butyrolactone, acetonitrile, propionitrile,methoxypropionitrile, acetone, furfural, N,N-dimethylformamide,N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide,N-formylmorpholine, and N-alkylpyrrolidones, for exampleN-methylpyrrolidone (NMP).

In other embodiments, the outflow stream can be passed through anabsorption column, wherein a solvent having a strong affinity foracetylene and preferably running counter-current to the outflow stream,absorbs acetylene from the flowing outflow stream. The absorbedacetylene can be removed from the solvent by heating the solvent in asecond column for restoring the solvent, and the restored solvent thencan be returned to the absorption column. Examples of solvents withstronger affinity for acetylene over other outflow gases includemethanol, ammonia, toluene, benzene, kerosene, butyrolactone,acetonitrile, propionitrile, methoxypropionitrile, acetone, furfural,N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide,N,N-diethylacetamide, N-formylmorpholine, and N-alkylpyrrolidones, e.g.,N-methylpyrrolidone (NMP).

iii. Chemical Reactions

In certain embodiments, higher-order hydrocarbons in the outflow streamcan be oxidized and thereby removed from the outflow stream. Forexample, certain higher-order hydrocarbons, particularly diacetylene andsubstituted acetylenes such as methylacetylene and vinylacetylene, canbe difficult to separate from acetylene, and they can be removed byconverting them into non-acetylenic compounds. To accomplish this, theoutflow stream can be passed through a column or vessel containing anoxidizing agent, such as a concentrated liquid acid capable of acting asan oxidizing agent, such as nitric acid, sulfuric acid, phosphoric acid,and the like. The higher-order hydrocarbons such as diacetylene and thesubstituted acetylenes can react with the oxidizing agent orconcentrated acid to create other hydrocarbon compounds that can be moreeasily separated from the outflow stream. In certain embodiments, theoutflow stream can be contacted with phosphoric acid on a solid supportto convert the higher-order hydrocarbons such as diacetylene and thesubstituted acetylenes into other hydrocarbon products that can be moreeasily separated from the outflow stream.

In certain embodiments, the outflow stream can be passed through acatalyst bed, using a catalyst that comprises transition metals,transition metal oxides, transition metal salts, or zeolites, in orderto convert various higher-order hydrocarbons into other carbon speciesthat are more readily removable from the gaseous product stream. Whenexposed to a suitable catalyst, these higher-order hydrocarbons can beconverted into a more easily removable compound by catalyst-drivenmechanisms such as polymerization, oxidation, hydrogenation, anddisproportionation. Depending on the mechanistic mode of catalyticconversion and the products obtained, these derivatives of thehigher-order hydrocarbons can be removed through further downstreamprocesses such as are described herein.

iv. Other Separation Technologies

In certain embodiments, higher-order hydrocarbons can be removed fromthe outflow stream by using a condenser, whereby the condenser collectsthese compounds on a high-surface-area material such as silica gel,activated carbon, activated alumina, zeolites, and the like. Forexample, certain higher-order hydrocarbons, e.g., methylacetylene andvinylacetylene, can be difficult to separate from acetylene in gaseousform, but their condensation points (5.01° C. and 10.3° C. respectively)contrast to the condensation point of acetylene (-84° C.) making themsuitable for removal via condensation from the outflow stream. In thisembodiment, a cold bed containing high surface area material attemperatures between -84° C. and 10° C. can effectively condense outhigher-order hydrocarbons from the outflow stream.

In certain embodiments, the outflow stream can be passed through a gasseparation membrane system, wherein gas molecules are separated via sizeexclusion. For example, smaller molecules, such as hydrogen, willpreferentially flow through the membrane element, forming a permeatestream, while larger molecules, such as methane, acetylene, higher-orderhydrocarbons, nitrogen, carbon dioxide, and any other larger molecules,do not flow through the membrane (depending on the porosity of themembrane), forming a retentate stream. In certain embodiments, thepermeate steam is a hydrogen-enriched stream and the retentate stream isa hydrogen depleted stream. Gas separation membrane elements can beformed from a variety of substances, for example: hollow fiber polymermembranes where the polymer can be polycarbonate, polyamide, orcellulose acetate; inorganic membranes where the inorganic material canbe mesoporous silica, zeolite, a metal-organic-framework, or mixed metaloxides; metal membranes where the metal can be palladium orpalladium-silver alloys; and the like. In embodiments, the feed for themembrane separation system can be the outflow stream from the plasmareactor, or it can be the collected gas from the first absorption columndescribed above, or some combination thereof.

Following certain of these outflow separation measures, in embodiments,the outflow stream, containing acetylene, hydrogen, and higher-orderhydrocarbons, can be further separated into its components so that thedesired gaseous products can be retrieved. In other embodiments, theoutflow stream is not subjected to further separation, for example if itis to be used for further chemical processing, or if it is provided to acustomer or end-user as a mixed stream.

f. Data Management and Safety Subsystems

Advantageously, the overall gas production system comprisesinterconnected data management subsystems and safety subsystems, so thatthe safety measures incorporated in these systems and methods areinformed by data collected about the system’s performance. Inembodiments, data management can include devices, procedures andalgorithms for data collection and performance diagnosis, and storagefacilities for recording and preserving data. In embodiments,performance diagnosis includes monitoring the state of the system withinnormal parameters to facilitate overall integration and control, andidentifying signs of upcoming or active failure states. Opticaldiagnostics can be directed at surveillance of the plasma region, forexample visible light cameras, mid-IR pyrometers, broadbandspectrometers, and the like. Apparatus diagnostics can include pressuretransducers, thermocouples, flow meters, microwave power sensors, andthe like. Other diagnostic equipment can be used as appropriate, forexample full-scale spectrometers and oscilloscopes. In embodiments,various diagnostic modalities can be integrated and monitoredautomatically and/or manually during a run.

In embodiments, the manual and automatic diagnostic procedures can beintegrated with safety procedures, which can include a fault-interlocksystem. In an embodiment, diagnostic input can be actively monitored byhardware and software. If an anomaly is detected, a fault signal can betriggered that activates a predetermined response pattern. For thosemost serious faults, such as a sudden corroborated pressure spike, animmediate automated “hard” shutdown can be triggered. For faults ofmoderate severity, where the consequences are less serious, a slowerautomated shutdown can be triggered, intended to stop operations overthe course of several seconds. For those faults where a parameter isoutside the expected range, but no major consequences are anticipated,the operator can be alerted, so that appropriate actions are taken torectify the situation and clear the fault without requiring a systemshutdown.

3. Exemplary Systems and Subsystems a. 100kW-Powered Plasma-BasedHydrocarbon Processing System

A plasma-based hydrocarbon processing system using plasma technology totransform hydrocarbon-containing inflow gas into acetylene and hydrogencan obtain a high degree of source hydrocarbon conversion in combinationwith a high degree of selectivity for the production of acetylene and/orhydrogen. The system described below uses a 100kW power supply togenerate the microwaves that form the plasma and effect the chemicaltransformations.

The central reaction of this process takes place when methane (derived,for example, from natural gas or biogas) or another C₂ - C₄ sourcehydrocarbon is fed into a microwave-energized region, where it breaksdown into a plasma. Without being bound by theory, it is postulated thatthe plasma drives the reaction from the source hydrocarbon to acetyleneand hydrogen by decomposing the hydrocarbon into excited CH_(x) radicalsthat recombine after the plasma energy state to form a spectrum ofhydrocarbon products and hydrogen. Using a C₂ - C₄ hydrocarbon as a feedimproves the overall process efficiency as compared to methane, while ahigh degree of selectivity to acetylene can be maintained. However,using methane as contained in natural gas or biogas has the advantage ofoperational efficiency and cost-effectiveness.

The methane conversion process in the 100 kW-powered processing system(i.e., using methane as may be found in a natural gas or biogas feed ora pure methane feed) uses approx. 9.5 kWhr per kg of acetylene productformed, with an acetylene yield of 90%: for the feed gas employed, about90% is converted to acetylene. The resulting product mix is influencedby the non-thermal nature of the plasma temperatures. The gastemperature is 3000-4000 K while the vibrational temperature andelectronic temperatures are two to three times higher, pushing thereaction equilibrium to form acetylene with a high selectivity, and withabundant hydrogen as a byproduct. Hydrogen produced by the plasmareaction can be recycled back into this system as a secondary feed gasthat is used for subsequent reactions, and/or it can be segregated as aseparate gas product. The co-presence of hydrogen and hydrocarbon ascomponents of the reaction reduces the reaction’s production of solids.To achieve a desirable proportion of hydrogen and methane for thereaction, the system recycles the produced hydrogen to participate inthe methane-based reactions, as described in more detail below.

i. Overall System

The 100kW-powered plasma-based hydrocarbon processing system comprisesfour subsystems: gas delivery, microwave, vacuum, and cooling. The gasdelivery subsystem contains two inflow lines. The first inflow line is afeed line conveying a mixed gas such as natural gas continuously sourcedfrom a local utility company or such as upgraded biogas, comprising amixture of predominantly methane, with small amounts of ethane, propane,carbon dioxide, and nitrogen (depending on the source of the raw mixedgas). This inflow can be scrubbed using conventional technologies beforeit enters the plasma reaction chamber, resulting in an almost puremethane stream, with other residual mixed gas components present on theorder of about 100 ppm. The total flow from this inflow line is scalablewith the overall microwave power of the system, with a flow ofapproximately about 3 SLM methane/kW microwave power. A second inflowline conveys recycled gas produced by the reactor that contains about 85to about 90% hydrogen, with small amounts of methane and nitrogen, forexample with amounts of unreacted nitrogen of about 5% to about 6%. Thetotal flow from this inflow line is also scaled with the overallmicrowave power of the system, with a flow of about 5 SLM recycledgas/kW microwave power.

Each inflow stream is sent into the plasma reaction chamber through itsown inlet that injects its flow into an entry region of a quartz tube toflow through the tube to the region in which the plasma is created. Theinlet for each inflow stream can be angled by a gas injector device toproduce the vortex flow that mixes the streams within the quartz tube asthey flow towards the reaction region, i.e., the plasma reactionchamber. The flow of gas entering through each inlet is controlled bymass flow controllers, adjusted to create a hydrogen-to-methane molarratio of 1.5 H₂ : 1 CH₄. As the methane is transformed into plasma, aspectrum of reaction products is formed within the plasma reactionchamber within the quartz tube.

When methane is used as a feed gas, about 95% of the methane undergoeschemical change within the plasma. Acetylene accounts for 95% of thehydrocarbons produced from the plasma-energized reactions, giving anoverall approximate 90% acetylene yield. Hydrogen is the other dominantreaction product from these reactions, accounting for approximately 80%of the total outflow stream by volume.

An exemplary 100kW-powered plasma-based hydrocarbon processing system900 is represented schematically by the block diagram shown in FIG. 9 .As shown in this Figure, a central reactor 902, comprising an injectionregion 904, a reaction region 908, and an outflow region 910, receivestwo separate gas streams: (1) a feed gas 912 containing a sourcehydrocarbon (for example the methane in a mixed gas such as natural gasor biogas, or a single C₁-C₄ hydrocarbon, or a customized blend of C₁-C₄hydrocarbons), and (2) a recycled gas flow 914 that includes hydrogenand mixed hydrocarbon-containing gas, and optionally unreactivenitrogen.

As schematically represented in the Figure, the inflow gas streams 912and 914 are processed in the reactor 902 to form an outflow stream 918that contains acetylene, hydrogen, and a small proportion of mixedhydrocarbons. The outflow stream 918 is then separated into its gaseouscomponents via a gas separation system 928 (e.g., adsorption,absorption, or a combination thereof) to yield an acetylene stream 920and a hydrogen-dominant gas stream 922 that contains hydrogen 936 and amixture of hydrocarbons 924. Thus, diverted from the main outflow stream918 by the gas separation system 928, the acetylene stream 920 can bepurified via further sequestration of impurities in a purificationsystem 926 to yield a purified acetylene gas product 932. Once theacetylene component 920 has been removed from the outflow stream 918,the remaining gas stream 922 is predominantly hydrogen along with amixture of hydrocarbon reaction products, i.e., is hydrogen-dominant.This hydrogen-dominant gas stream 922 can be subjected to furtherseparation if desired, so that hydrogen gas is isolated as a distinctgas stream 930. The hydrogen gas product stream 930 can be furtherpurified as necessary and sold as a product, or it can be recycled backinto the reactor 902 for further reaction with the feed gas 912. In thissystem 900, instead of recycling the hydrogen gas product stream 930,the mixed hydrogen-dominant gas stream 922 is recycled to form therecycled gas flow 914, which is reintroduced into the reactor 902 forfurther reaction with the feed gas 912. Mass flow controllers 940 and942 coordinate the inflow of the feed gas 912 and recycled gas 914 intothe reactor 902 to create the desired ratio of hydrogen to methane (orhydrogen to other source hydrocarbon) in the reactor 902.

ii. Reactor

The reactor identified in FIG. 9 is shown in more detail in FIG. 10 .FIG. 10 depicts schematically the reactor 1002, its components, and itsintegration with the microwave subsystem 1004. As depicted, and asoutlined by the grey shadowed box, the microwave subsystem includes apower supply and magnetron complex 1016 for producing the microwaves,and a waveguide assembly 1020 for guiding the microwaves towards areaction region 1012 within the quartz tube where the microwave plasma1018 is formed. As shown in FIG. 10 , a quartz tube 1008 contains thecomponents of the reactor 1002: the injection region 1010, the reactionregion or reaction chamber 1012, and the outflow region 1014. Within thequartz tube 1008, the microwave plasma 1018 is generated by themicrowaves (not shown) aimed at the gas flow 1006 within the tube 1008,thereby effecting the transformation of source hydrocarbon into hydrogenand various hydrocarbon-derived products. This quartz tube 1008 isinserted through the broad wall of a microwave waveguide assembly 1020.The size of the quartz tube 1008 depends on the amount of microwavepower used in the system. For the depicted system using 100 kW of powerto produce microwaves, the quartz tube 1008 has an 80 mm outer diameter,a 75 mm inner diameter, a length of 1700 mm, and is maintained at apressure of about 70 Torr by downstream vacuum pumps (not shown). Therelationship of the quartz tube 1008 and the microwave subsystem 1004 isdescribed below in more detail.

As shown in FIG. 10 , the recycled gas stream 1022 mixes with the feedgas stream 1024 within the injection region 1010 of the reactor 1002,each stream entering the injection region 1010 of the reactor 1002through its own inlet (not shown). The passage of each gas streamthrough the gas injector device 1032 (also shown schematically in FIGS.11 ) into the reactor 1002 affects its direction, flow rate, andvelocity. As depicted in FIG. 10 , an optional gas stream or gas streams1028 can be directed into the injection region 1010, to be blended withthe recycled gas stream 1022 and the feed gas stream 1024 to create avortical gas flow 1006. After mixing, the gases in the gas flow 1006flow distally through the quartz tube 1008, to encounter microwaveenergy produced by the power supply and magnetron complex 1016 anddelivered through the waveguide assembly 1020 into the reaction region1012 of the reactor 1002. The interaction of the microwave energy andthe gas within the reaction region 1012 of the reactor 1002 produces theplasma 1018. The outflow gaseous stream 1034 containing the reactionproducts emerges from the plasma 1018 to enter the outflow region 1038of the quartz tube 1008, to be passed out of the reactor 1002 forfurther separation 1040. As shown in this Figure, a microwave subsystem1004 includes the power supply and magnetron complex 1016 and thewaveguide assembly 1020; not shown in this Figure are additionalelements of the microwave subsystem that are illustrated and describedin the Figures below.

FIG. 11A is a cross-sectional schematic view (not to scale) of anembodiment of a gas injector suitable for use with the 100kW-poweredplasma-based hydrocarbon processing system, such as the gas injector1032 depicted in FIG. 10 . For exemplary purposes, the cross-sectionalview in FIG. 11A corresponds to a cross-section taken at the line A-A′in FIG. 10 . FIG. 11A shows a gas injector 1106 situated in a reactionchamber 1102 of a plasma reactor 1100 and providing a plurality of gasflows into the reaction chamber 1102 for those gases to encountermicrowave energy as described above. As shown in this Figure, the gasinjector 1106 provides flow paths for two distinct gas streams into thereactor 1102, with each gas stream directed through its own nozzle andflow path within the gas injector device 1106 and into the reactor 1102.As illustrated in FIG. 11A, there are four injector ports, two for therecycled gas flow 1104 a and 1104 b, and two for the feed gas stream1108 a and 1108 b. In the Figure, the two recycled gas nozzles 1104 aand 1104 b are in fluid communication with a first central flow channel1110 through which the recycled gas stream enters the gas injector 1106and is directed to the recycled gas nozzles 1104 a and 1104 b.Similarly, there is a second centrally-disposed channel 1112 in the gasinjector 1106 for feed gas, where this channel is discrete from thefirst central flow channel 1110 for the recycled gas stream. There aretwo nozzles for feed gas 1108 a and 1108 b, in fluid communication withthe second centrally-disposed channel 1112, with these nozzles 108 a and1108 b entering the reactor 1102 at a different level than the nozzlesfor the recycled gas 1104 a and 1104 b. The nozzles for both types ofgas flow are oriented in directions that are conducive for the formationof a vortex gas flow within the reactor 1102. The channel for recycledgases 1110 and the channel for feed gas 1112 do not intersect with eachother, but rather provide separate gas streams into their respectivenozzles 1104 a/1104 b and 1108 a/1108 b; neither do the nozzlesintersect with each other, but rather provide their gas streamsseparately into the reactor 1102. The gas flow through each of thenozzles can be coordinated with the other gas flows in the other nozzlesin terms of flow rate, path length, and pressure drop.

It would be understood by skilled artisans that the relative position ofthe feed gas channel 1112 and the recycled gas channel 1110 can berearranged, for example, as parallel channels, as helices, at differentlevels within the gas injector 1106, or as other arrangements besidesthose shown in FIG. 11A, provided that the channels for each gas arekept separate from each other in the gas injector 1106, and furtherprovided that each distinct gas stream enters the reactor 1102 throughits own discrete nozzle or nozzles. Moreover, the number, configuration,and direction of the nozzles can be varied, provided that the gas streamfor each component gas (i.e., feed gas and recycled gas and any optionaladditional gas) enters the reactor through its own nozzle, withoutcommingling with the other gas stream.

FIG. 11B is a cross-sectional schematic view (not to scale) of anotherembodiment of a gas injector suitable for use with the 100kW-poweredplasma-based hydrocarbon processing system, such as the gas injector1032 depicted in FIG. 10 . For exemplary purposes, the cross-sectionalview in FIG. 11B corresponds to a cross-section taken at the line A-A′in FIG. 10 . FIG. 11B shows a gas injector 1156 situated in a reactionchamber 1152 of a plasma reactor 1150 and providing a plurality of gasflows into the reaction chamber 1152 for those gases to encountermicrowave energy as described above. As shown in this Figure, the gasinjector 1156 provides flow paths for two distinct gas streams into thereactor 1152, with each gas stream directed through its own set ofnozzles within the gas injector device 1156 and into the reactor 1152.As illustrated in FIG. 11B, there are eight injector ports or nozzles,four (1154 a, 1154 b, 1154 c, and 1154 d) for a first gas flow, forexample the recycled gas flow, and four (1158 a. 1158 b, 1158 c, and1158 d) for a second gas flow, for example a feed gas stream. In theFigure, the four nozzles for the first gas flow (1154 a, 1154 b, 1154 c,and 1154 d) are in fluid communication with a central flow channel 1162through which the first gas stream enters the gas injector 1156 and isdirected to the appropriate nozzles 1154 a, 1154 b, 1154 c, and 1154 d.The nozzles 1158 a, 1158 b, 1158 c, and 1158 d for the second gas floware each supplied by a separate flow channel 1160 a, 1160 b, 1160 c, and1160 d respectively. Other arrangements of the flow channels to supplythe nozzles 1158 a, 1158 b, 1158 c, and 1158 d for the second gas flowcan be envisioned, provided that the flow channels for the second gasflow do not permit the second gas flow to be commingled with the firstgas flow. Instead, each gas flow is conveyed with its own discrete setof nozzles and its own flow channel(s). The nozzles for the first gasflow 1154 a, 1154 b, 1154 c, and 1154 d, and the nozzles for the secondgas flow 1158 a, 1158 b, 1158 c, and 1158 d, are oriented in directionsthat are conducive for the formation of a vortex gas flow within thereactor 1152. The gas flow through each of the nozzles can becoordinated with the other gas flows in the other nozzles in terms offlow rate, path length, and pressure drop.

iii. Microwave Subsystem

The microwave subsystem shown in FIG. 10 is depicted schematically inFIG. 12 , and in more detail. Referring to FIG. 10 , a reaction region1012 of the reactor 1002 can be seen intersecting with the waveguideassembly 1020, wherein the microwaves are directed at the gas flow 1006as it enters the reaction region 1012 to form the plasma 1018. Themicrowave subsystem 1004 is responsible for generating the microwavesand directing them towards the reactor 1002.

The microwave subsystem is shown in more detail in FIG. 12 . As shown inthis Figure, the microwave subsystem 1200 comprises a power supply 1208,a magnetron 1210, a waveguide assembly 1202 (which includes a waveguide1212 and certain other standard microwave components as describedbelow), and an applicator 1204. The power supply 1208 converts 480 V,150A AC electrical power to 20kV21kV, 5.8A of low-ripple DC power with aconversion of 96% to energize the magnetron 1210. The magnetron 1210,rated at 100 kW, produces continuous microwave power at 83-89%efficiency. The microwaves produced are in the L-band frequency range,approximately 915 MHz. The microwaves are launched into a waveguideassembly 1202, within which a waveguide 1212 directs them through theother components of the system and to the applicator 1204, where theyinteract with the gas/plasma in the plasma reaction chamber 1214. Thewaveguide 1212 features a 90-degree bend 1216. One of the components ofthe waveguide is an isolator 1218 with an attached water load 1220,located distal to the magnetron 1210, to protect the magnetron 1210 fromreflected (un-absorbed) microwaves by directing them with a ferriticcore 1222 to the water load 1220. The other components of the waveguideassembly 1202 allow the microwaves to be guided towards the plasmareaction chamber 1214 and tuned to optimize the creation of the plasmatherein. The applicator 1204 provides the interface between themicrowaves and the quartz tube 1224 within which the plasma is created.Plasma is formed within the plasma reaction chamber 1214, the region ofthe quartz tube 1224 within which the chemical transformations takeplace. As shown in cross-section in FIG. 12 , the quartz tube 1224 isdisposed within, but is separated from, the applicator 1204 by an airgap (not labeled).

When the plasma is off and the microwaves are on, a standing wave isformed in the applicator 1204 between the 3-stub tuner 1230 and asliding shorting plate 1232 on the end of the applicator 1204, such thatthe electric field is sufficient to initiate breakdown of the gasmolecules in the quartz tube. Microwave energy entering the applicator1204 is tuned to peak at the center of the plasma reaction chamber 1214,using the shorting plate 1232 as needed to change the length of theplasma reaction chamber 1214 and using the 3-stub tuner 1230 to changethe phase of the incoming microwaves. Once the plasma has beeninitiated, the stub locations in the tuner 1230 can be alteredpreferentially to match the microwave power to the plasma, minimizingun-absorbed power. The 3-stub tuner 1230 contains power and phasesensors (not shown) and can algorithmically adjust the motor-drivenstubs to minimize un-absorbed power. A dual-directional coupler 1234,which contains two small pinholes that couple microwaves with a knownattenuation, is included in the waveguide 1212 proximal to the 3-stubtuner 1230. Power meters (not shown) are connected to these pinholeports and convert the microwave power into a voltage, outputting forwardand reflected power measurements. A thin quartz window 1238 is addedinto the waveguide system to prevent environmental debris and dust fromentering the waveguide components.

b. Torch System for Acetylene Production

In embodiments, a plasma-based hydrocarbon processing system forproducing acetylene and hydrogen can be of any scale and can deliver arange of purities and acetylene concentrations, depending on the desiredend use. Plasma-based hydrocarbon processing systems as describedpreviously can be designed for small scale applications and can beadapted to the needs of the end user. To facilitate this customization,a plasma-based hydrocarbon processing system can be configured so thatthe outflow (effluent) stream from the reactor is separated into gasstreams having different compositions, for example, a stream having ahigher concentration of acetylene and a stream having a higherconcentration of hydrogen. Small-scale plasma-based hydrocarbonprocessing systems can be designed to deliver pure gas streams, or theycan deliver acetylene-hydrogen mixtures, with or without other gasesincluded in the output gas flow. A small-scale system or “mini-unit” asdescribed above can be designed to produce only acetylene-hydrogenmixtures in its reactor, with gas effluent varying from 0.5%-75%acetylene, therefore minimizing the amount of separation required andreducing the complexity of the system. In embodiments, the end user canmanipulate the parameters of the separation subsystem to produce adesired composition of acetylene admixed with hydrogen; in embodiments,the parameters of the microwave plasma reactor module in the mini-unitcan be adjusted as well, although for more extensive parametercustomization, a larger unit is desirable.

In an embodiment, the overall size of the plasma-based hydrocarbonprocessing system can be scaled, for example from a smaller scale unitsuch as a table-sized mini-unit (e.g., 4 feet wide by 8 feet long by 4feet tall) to a large-scale unit that is 20x20x20 feet or larger. In anembodiment, the plasma-based hydrocarbon processing system can be sizedso that it is portable. Desirable sizing for a portable unit ranges fromthe table-sized dimensions (e.g., 4x8x4) to the size of a standardshipping container. While shipping containers vary in size, a standard20-foot ISO shipping container size would allow transportation of aportable-sized unit; such containers are typically about 8 feet wide, 20feet long, and 8.5 to 9.5 feet high. Other, smaller, shipping containerscan be used for smaller portable devices, for example, those havinglengths of 10 feet or 8 feet, combined with height and width dimensionsas mentioned above.

Such a small-scale system can be attached to small end-user apparatus(e.g., welding torches such as acetylene or oxy-acetylene torches) or tosmall storage facilities or storage tanks. In an embodiment, a 5 kWplasma-based hydrocarbon processing system mini-unit with dimensions of4 feet wide by 8 feet long by 4 feet tall can produce acetylene-hydrogenmixtures of greater than 50% acetylene, in an amount sufficient to feedat least 5 oxy-fuel cutting torches of concurrent, continuous use. Inembodiments, power ranges for a plasma-based hydrocarbon processingsystem mini-unit can range from about 1 kW to about 500 kW, with powerranges selected for desired commercial uses. A plasma-based hydrocarbonprocessing system such as this can be designed to be portable. Asdescribed above, larger units, for example up to the size of a standardISO 20-foot shipping container, can also be designed to be portable. Inembodiments, a portable plasma-based hydrocarbon processing system canbe deployed to construction sites, demolition sites, shipyards, orremote operations like pipelines or offshore oil rigs, depending on theavailability of a mixed gas stream such as natural gas or biogas,electricity, and water.

FIG. 13 provides a block diagram of a small scale and scalableplasma-based hydrocarbon processing system 1300 suitable for industrialuses. As shown in FIG. 13 , a plasma reactor 1302 substantially asdescribed above has an input feed gas 1304 comprising a hydrocarbon suchas methane, ethane, propane, butane, and the like, and derived fromtanks or pipelines such as a natural gas line or a biogas tank or line.This input feed gas 1304 has a preselected inflow calibrated to producean outflow (effluent) gas flow 1306 from the system 1300 ultimatelysuitable for a particular industrial purpose, for example metal cutting.In embodiments, an input feed gas 1304 such as methane or amethane-dense mixture such as natural gas or biogas can be used. Inembodiments, a liquid source of an input feed gas 1304 such as propaneor butane is advantageous, since such feed gas sources may be readilyavailable in certain regions or facilities where a native gas sourcesuch as natural gas or biogas is not available.

In this Figure, the direction of gas flow is indicated by the arrow 1308and other directional arrows. As an example of gas flows useful in thesystem 1300, a gas inflow within the range from about 0 to about 50 SLMcan be selected; in an embodiment, a gas inflow of 5 SLM can produce agas outflow of about 10 SLM. In embodiments, the input feed gas 1304enters the plasma reactor 1302 as a sole gas input. In otherembodiments, a separate gas input from a recycled gas stream 1310 entersthe plasma reactor 1302 through a separate inflow nozzle (not shown), tobe combined with the input feed gas 1304 within the plasma reactor 1302,for example using a gas injector (not shown) as described in previousFigures.

In an embodiment, the outflow 1306 from the plasma reactor 1302 containsabout 14% acetylene, 84% hydrogen, and 2% methane, and it can be furtherprocessed by other components of the system. Entrained in the gaseousoutflow 1306 are various carbon species byproducts, includinghigher-order carbon products and carbon particles, that can be removedprior to delivering a gas product to an end-user in certain embodiments.These byproducts can be removed in solid and liquid traps 1312, throughwhich the outflow gas 1306 passes after being processed in the plasmareactor 1302. After the byproducts are removed, the gas stream 1306 isprocessed through a hydrogen separation system 1314, which can include ahydrogen separation membrane system, a short-cycle temperature swingadsorber, or a pressure swing adsorber that removes hydrogen. Suchprocessing allows an acetylene-rich stream 1318 to be separated from ahydrogen-rich stream 1320, with the acetylene-rich stream 1318 beingavailable to the end-user for industrial purposes, e.g., metal cutting.In other embodiments, there is no advantage to removing the higher-ordercarbon products, for example if the gaseous effluent is to be used forwelding or other industrial uses where a purified acetylene stream isunnecessary. However, it is understood that higher-order carbon productscan foul hydrogen separation membranes, so that these species should beremoved if a hydrogen separation membrane system is used; alternatively,if a mixed effluent stream that includes the higher-order carbonproducts is commercially advantageous, a hydrogen separation system suchas a short-cycle temperature swing adsorber or pressure swing adsorbercan be used instead of a hydrogen separation membrane system.

As shown in the Figure, the acetylene-rich stream 1318, having beenprocessed to remove higher-order carbon products and hydrogen, can bedirected to various end uses or storage 1322. For example, theacetylene-rich stream 1318 can be directed into a pressurized tank, fromwhich end-users can withdraw the gas mixture for use in metal cuttingtorches; advantageously, if the acetylene-rich stream 1318 is stored,the plasma-based hydrocarbon processing system can be run intermittentlyon an as-needed basis to fill the tank(s) for later use. In anembodiment, the acetylene-rich stream 1318 can contain about 50%acetylene, along with other components such as hydrogen, methane, andother gaseous additives as applicable. The acetylene-rich stream 1318can be produced at a flow of about 2.1. SLM. In an embodiment, thehydrogen-rich stream 1320 can contain about 4% acetylene and 96%hydrogen, with a total flow of about 7.9 SLM. In embodiments, two ormore separation membrane systems can be employed to increase theconcentration of acetylene in the acetylene-rich product stream 1318,although a small-scale system can be designed with a single separationmembrane system in order to limit the overall size of the apparatus.

In the plasma-based hydrocarbon processing system embodiment illustratedin FIG. 13 , the hydrogen-rich stream 1320 can be directed through asplitter 1322, which can separate the hydrogen-rich stream 1320 into twosubstreams 1320 a and 1320 b, one (1320 a) for end uses, disposal,and/or storage, and one (1320 b) for recycling as a recycled gas stream1310 into the plasma reactor 1302, where it can be processed along withthe input feed gas 1304. The splitter 1322 can be formed from componentsfamiliar to those of skill in the art, such as Y-valves, mass flowcontrollers and the like. The hydrogen-rich substream 1320 a that is notrecycled can be vented, disposed of, collected, burned, or otherwiseused, as required by the specific industrial setting.

The hydrogen-rich substream 1320 b used for recycling can have the samecomposition as the substream 1320 a that is directed to end uses,disposal, and/or storage. In an embodiment, a recycle flow 1310 of about5 SLM can be redirected into the plasma reactor 1302, having acomposition of about 97.5% hydrogen and 2.5% acetylene, yielding arecycle flow of about 5 SLM hydrogen. With a recycled stream 1310combined with the input feed gas 1304 to fuel chemical transformationsin the plasma reactor 1302, an outflow gas 1306 is produced, asdescribed above. In embodiments, the proportion for recycling can betuned, based on the user’s requirements. For recycling, a mass flowcontroller that meters the amount of hydrogen-rich gas 1320 b forrecycling offers particular consistency, with the remainder directed toend-uses, disposal, or storage.

FIG. 14 shows, in more detail, a modular plasma-based hydrocarbonprocessing system 1400 suitable for small-scale or larger-scale use,with arrows showing directions for gas flow. As shown in FIG. 14 , a gaspipeline 1404, for example a natural gas pipeline, can provide theinflow gas for the microwave plasma reactor 1402, although any source ofinflow gas can be used (a supply tank containing the gas, for example,as would be available for C₁-C₄ alkanes, or a line or tank deliveringbiogas). The inflow gas can be supplemented by a recycled stream 1408containing a hydrogen-rich gas. Following processing in the microwaveplasma reactor 1402, the outflow (effluent) gas passes through a heavyliquids trap 1412 that removes the higher-order hydrocarbons using acombination of a cold trap and/or a carbon adsorber. As a next stage,the outflow gas passes through a filter 1414 that removes particulatematter, for example carbon soot. The gas pressure is then adjusted by avacuum pump 1418 and then the gas is compressed by a compressor 1422 topass through a hydrogen separator 1424. The plasma reactor 1402, theheavy liquids trap 1412, the solids filter 1414, and the vacuum pump1418 are grouped together as the reactor subsystem 1420. This can belocated in proximity to the hydrogen recycle subsystem 1410 and theeffluent management subsystem 1434, or these subsystems can be in fluidcommunication with each other but arranged remotely from each other, asis convenient for a particular industrial application.

As mentioned previously, the hydrogen separator 1424 can include one ormore hydrogen separation units; in an exemplary embodiment, eachhydrogen separation unit can contain one or more hydrogen separationmembranes, but other configurations and separator technologies (forexample, a short-cycle temperature swing adsorber describe previously ora pressure swing adsorber technology to separate hydrogen) can beemployed. The configurations of the hydrogen separator units areadaptable to permit lesser or greater acetylene enrichment in theeffluent acetylene-rich stream 1428. Depending on the desired industrialuse, this effluent stream 1428 can be used directly as a cutting stream,or it can be stored as a product stream. In an embodiment, the gasremaining after the acetylene-rich stream 1424 is removed contains alarge proportion of hydrogen. As previously described, thishydrogen-rich stream can be split into two substreams in a splitter1432, with one stream 1408 designated for recycle, and one stream 1430for disposal, venting, burning, commercialization, or other uses asdesired.

Effluent management subsystems, substantially as described previously,can be integrated with the reactor subsystem (including a gas deliverysubsystem, a microwave subsystem, and a vacuum subsystem, previouslydescribed but not shown in FIG. 14 ) within a single mini-unit forspecific applications. The size, number, and complexity of thecomponents required for the effluent separation processes can affect thesize of the system overall. In an embodiment, a single plasma reactorcan utilize a single hydrogen separation subsystem to provide a smallfootprint, with the subsystem including one or two hydrogen-separatingmembranes or other separation subsystem technologies, such as pressureswing adsorption. In an embodiment, separation subsystems, for examplefor hydrogen separation, can be integrated with the plasma-basedhydrocarbon processing system.

In an embodiment of a modular plasma-based hydrocarbon processing systemusing a single hydrogen separation unit with a single separationmembrane, the outflow gas from the reactor can contain the followinggaseous components, at a flow rate of 10 SLM: 14% acetylene, 81%hydrogen, 2% methane, and 3% nitrogen. Following processing through ahydrogen separation unit having a single separation membrane, ahydrogen-rich stream is formed, containing the following gaseouscomponents at a flow rate of 7 SLM: 4% acetylene, 96% hydrogen.Simultaneously, an acetylene-rich stream is formed, containing thefollowing gaseous components at a flow rate of 3 SLM: 50% acetylene, 27%hydrogen, 9% methane, and 14% nitrogen. Using this process, 93.75%acetylene retention is accomplished in the acetylene-rich stream, and86.5% of hydrogen is recycled. The flow rates and mol ratios of thecomponents of the various gas streams for the one-membrane hydrogenseparation system are shown in Table 3 below:

TABLE 3 Plasma Reactor Effluent Acetylene-rich stream Hydrogen-richstream Vent/burn Recycle Stream Flow Rate (SLM) mol ratio Flow Rate(SLM) mol ratio Flow Rate (SLM) mol ratio Flow Rate (SLM) mol ratio FlowRate (SLM) mol ratio H₂ 8.1 0.81 0.567 0.268 7.53 0.956 3.53 0.956 40.956 CH₄ 0.2 0.02 0.2 0.094 0 0 0 0 0 0 N₂ 0.3 0.03 0.3 0.142 0 0 0 0 00 C₂H₂ 1.4 0.14 1.05 0.496 0.35 0.044 0.164 0.044 0.186 0.044 Total 102.12 7.88 3.694 4.186

A double-membrane hydrogen separation unit can extract more hydrogenfrom the reactor’s outflow gas, yielding a hydrogen-rich streamcontaining 1.2% acetylene and 98.8% hydrogen, at a flow of 7 SLM. Withthis system, an acetylene-rich stream is formed containing the followinggaseous components at a flow rate of 3 SLM: 45% acetylene, 38% hydrogen,7% methane, and 10% nitrogen. The flow rates and mol ratios of thecomponents of the various gas streams for the two-membrane hydrogenseparation system are shown in Table 4 below:

TABLE 4 Plasma Reactor Effluent Acetylene-rich stream Hydrogen-richstream Vent/burn Recycle Stream Flow Rate (SLM) mol ratio Flow Rate(SLM) mol ratio Flow Rate (SLM) mol ratio Flow Rate (SLM) mol ratio FlowRate (SLM) mol ratio H2 8.1 0.81 1.09 0.376 7.006 0.988 3.53 0.988 40.988 CH4 0.2 0.02 0.2 0.069 0 0 0 0 0 0 N2 0.3 0.03 0.3 0.103 0 0 0 0 00 C2H2 1.4 0.14 1.05 0.452 0.088 0.012 0.038 0.012 0.05 0.012 Total 102.12 7.094 3.568 4.05

A wide variety of industrial uses can be envisioned for small scale ormodular plasma-based hydrocarbon processing systems as described herein.As mentioned above, a major industrial use for acetylene is in themetalworking industry, for example in metal cutting. For these purposes,an appropriately sized plasma-based hydrocarbon processing system inaccordance with this disclosure can be used directly or via storagetanks to provide fuel for metal cutting. In addition, the plasma-basedhydrocarbon processing system can be coupled with other systems toprovide product versatility and to increase efficiency in themetalworking industry. As an example, in oxy-acetylene steel cuttingfacilities, the plasma-based hydrocarbon processing system can be usedin conjunction with air separation units (ASUs). The ASU can separateair into nitrogen-rich and oxygen-rich streams, which can then becombined with the gas stream(s) used by or produced by microwave plasmareactor unit. Using this combination of apparatus, an operator cangenerate all the gas feedstock required for steel fabrication on-site.

4. Integrated Industrial Applications

In embodiments, a plasma-based hydrocarbon processing system, forproducing acetylene and hydrogen, as described above, can deliver eitherof these products into subsystems for further processing, so that afully integrated industrial application is constructed that incorporatesprecursor production (i.e., acetylene and/or hydrogen produced by theplasma-based hydrocarbon processing system) and precursor utilization toform industrially useful products.

a. Vinyl Chloride Monomer (VCM) Manufacture

As an example, the acetylene produced by the plasma-based hydrocarbonprocessing system can act as the precursor for other industrialprocesses, such as VCM manufacturing. A plasma-based hydrocarbonprocessing system as described above can be modified so that itmaximizes and optimizes the acetylene produced, and it can be integratedwith those processes required to convert the acetylene into VCM.

In exemplary embodiments, an integrated process for VCM manufacture canbe envisioned as set forth in FIG. 15A. As shown in FIG. 15A, a systemfor VCM production 1500 can be based on a plasma-based hydrocarbonprocessing system, using certain of the components of the plasma-basedhydrocarbon processing system that have already been described. In moredetail, FIG. 15A depicts a system for VCM production 1500 comprising aplasma-based hydrocarbon processor 1502, a VCM reactor 1506, and aplurality of separators 1520, 1522, and 1524. The plasma-basedhydrocarbon processor 1502 operates in keeping with the principlesdescribed and illustrated in the Figures above; it can use any of theplasma-based hydrocarbon processing systems described herein. Asintegrated with the other components of the VCM production system 1500,the plasma-based hydrocarbon processor 1502 is responsible forconverting one or more inflow gases into a mixture of gaseous productscontained in an outflow stream emerging from a plasma reaction chamber,where the plasma reaction chamber contains the plasma that has beengenerated by a microwave subsystem. Details of these components of theplasma-based hydrocarbon reactor are substantially similar to analogouscomponents described herein, and as illustrated in previous Figures.

An embodiment of the plasma-based hydrocarbon processor 1502 suitablefor use with the integrated VCM production system 1500 is shown in moredetail in FIG. 15B. The embodiment depicted in FIG. 15B shows oneexample of a plasma-based hydrocarbon processor 1502 suitable for usewith the integrated VCM production system shown in FIG. 15A. Otherembodiments of plasma-based hydrocarbon processors as have beendescribed herein can also be used with the VCM production system 1500.FIG. 15B shows a plasma-based hydrocarbon processor 1502 having a gasdelivery subsystem 1510 that delivers one or more inflow gases 1504 a,1504 b, 1504 c into the plasma reaction chamber 1514 where they areenergized by the microwave subsystem 1508 to form a plasma that yieldschemical products that emerge from the plasma reaction chamber 1514 toform an outflow stream (or effluent stream) 1512 of outflow gasproducts. The outflow stream (or effluent stream) 1512 is then subjectedto downstream processing 1510, to be described in more detail inconjunction with FIG. 15A. The inflow gases 1504 a, 1504 b, 1504 c caninclude hydrogen gas, a hydrocarbon such as methane (either in pure formor as a component of a gas mixture such as natural gas), and othergases, all as previously described for the plasma-based hydrocarbonprocessing systems disclosed herein. In embodiments, one or more of theinflow gases 1504 a, 1504 b, and 1504 c, can be a recycled gas. Theoutflow stream 1512 comprises acetylene and hydrogen, as previouslydescribed for the various embodiments of plasma-based hydrocarbonprocessing systems as set forth above.

Returning to FIG. 15A, the plasma-based hydrocarbon processor 1502receives the one or more inflow gases 1504 a, 1504 b, 1504 c, where atleast one of the gases is a hydrocarbon gas, for example methane. Inembodiments, the inflow hydrocarbon gas can be natural gas, as describedabove for the plasma-based hydrocarbon processing system, whichcomprises methane. Emanating from the plasma-based hydrocarbon processor1502 is an outflow stream (or effluent stream) 1512 containing a mixtureof acetylene, hydrogen, higher acetylenes and other products includinghigher hydrocarbons (collectively, (C₃ ⁺)). To prepare the outflowstream 1512 for use in the VCM reactor 1506, the outflow stream 1512 ispassed through the first of a plurality of separators, a firstseparation system 1520, which is an effluent separator that removes thehigher acetylenes and aromatics (C₃ ⁺) from the outflow stream 1512,yielding a purified effluent stream 1530 that is delivered to the VCMreactor 1506. A stream of hydrogen chloride gas 1526 is also deliveredto the VCM reactor 1506. The acetylene contained in the purifiedeffluent stream 1530 combines with the hydrogen chloride gas 1524 in theVCM reactor 1506 to produce VCM, as illustrated by the followingformula:

Emerging from the VCM reactor 1506 is a VCM reactor effluent 1528 thatenters a second separation system 1522. This second separation system1522 is a condensing system comprising a compressor 1522 a to compressthe VCM reactor effluent 1528 and a chiller 1522 b that lowers thetemperature of the VCM reactor effluent 1528, allowing the VCM tocondense out of the VCM reactor effluent 1528 as a liquid, which canthen be removed from the fluid stream by the liquid-gas separator 1522 cas a liquid form of VCM 1536. The chiller 1522 b can be operated bycirculating refrigerant 1522 d or any other mechanism familiar toartisans of ordinary skill. A stream of residual gas 1532 emerges fromthe liquid-gas separator 1522 c for further processing by a thirdseparation system 1524, which separates purified hydrogen from theresidual gas 1532, leaving behind a stream of gas 1538 that can berecycled into the plasma-based hydrocarbon processor 1502.

In an embodiment, a plasma-based hydrocarbon processor 1502 can be setup substantially in the form of the 100kw plasma-based hydrocarbonprocessing system described above; while this system has been describedas having a magnetron power of 100 kW, it is understood that otheramounts of power for the system can also be employed to power theplasma-based hydrocarbon processor. In this exemplary embodiment, theinflow gases 1504 a and 1504 b for the plasma-based hydrocarbonprocessor are natural gas (mostly methane) and recycle gas (mostlyhydrogen). These inflow gases 1504 a and 1504 b react in theplasma-based hydrocarbon processor 1502 to produce the acetylene in theoutflow stream 1512. As has been already detailed above for theplasma-based hydrocarbon reactor technology, the outflow stream 1512comprises other substances as well, including hydrogen, higheracetylenes, aromatics, etc. The outflow stream 1512 is thereforeprocessed by the first separation system 1520 to remove the higherhydrocarbons (C₃ ⁺), such as the higher acetylenes and aromatics. As hasbeen described above, effluent separation subsystems suitable for use ascomponents of the first separation system 1520 can include prescrubbers,temperature swing adsorbers, and the like. As a result of its encounterwith the first separation system 1520, the outflow stream 1512 emanatingfrom the plasma-based hydrocarbon processor 1502 is purified of thesehigher hydrocarbons (C₃ ⁺) and emerges as the purified effluent stream1530. The purified effluent stream 1530 is combined with hydrogenchloride gas 1526 within VCM reactor 1506, where a reaction between thetwo gases is catalyzed to form VCM; the VCM thus formed is dischargedfrom the VCM reactor in a VCM-containing gas stream, the VCM reactoreffluent 1528. The VCM reactor effluent 1528 is then processed by thesecond separation system 1522, which condenses the liquid VCM 1536 andallows the residual gas 1532 to pass through to the third separationsystem 1524, which provides a hydrogen separator that separates thepurified hydrogen product 1534 from the recycle gas stream 1538returning to the reactor 1502. The hydrogen separator can be, forexample, an H₂ membrane, an H₂ pressure swing adsorber, or othertechnologies described herein for hydrogen separation. While the systemfor VCM production 1500 has been exemplified by reference to the 100kwplasma-based hydrocarbon processing system described above, it isunderstood that other versions of the plasma-based hydrocarbonprocessing systems disclosed herein are also suitable for use in thisintegrated system and method. It is understood that the system for VCMproduction 1500 can use a plasma-based hydrocarbon processing system ofany scale, and delivers a range of purities and acetyleneconcentrations. As an example, the plasma-based hydrocarbon processingsystems described above for small scale applications can be used withthe system for VCM production.

FIG. 16 depicts an alternative embodiment of a system for VCM productionintegrated with a plasma-based hydrocarbon processing system, usingcertain of the components of the plasma-based hydrocarbon processingsystem that have already been described. In more detail, FIG. 16 depictsa system for VCM production 1600 comprising a plasma-based hydrocarbonprocessor 1602, a VCM reactor 1606, and a plurality of separators 1620,1622, and 1624. The plasma-based hydrocarbon processor 1602 operatesaccording to the principles described and illustrated in the Figuresabove; it can use any of the plasma-based hydrocarbon processing systemsdescribed previously. As integrated with the other components of the VCMproduction system 1600, the plasma-based hydrocarbon processor 1602 isresponsible for converting one or more inflow gases 1604 into a mixtureof gaseous products contained in an outflow stream emerging from aplasma reaction chamber (not shown), where the plasma reaction chambercontains the plasma that has been generated by a microwave subsystem(not shown). Details of these components of the plasma-based hydrocarbonreactor are substantially similar to analogous components describedabove and illustrated in the foregoing Figures. However, while thecomponents of the system 1600 are substantially similar to thoseillustrated in FIG. 15A and FIG. 15B, their arrangement is different. Asshown in FIG. 16 , the inflow gas 1604 enters the plasma-basedhydrocarbon processor 1602, where it mixes with any other inflow gases(including recycled gas 1638) and where it is transformed into anacetylene-containing effluent stream 1612 via its encounter with theplasma within the plasma-based hydrocarbon processor 1602. The effluentstream 1612 then passes into a first separation system 1620, wherehigher hydrocarbons (C₃ ⁺) (e.g., acetylenes and aromatic compounds) areremoved. The purified effluent stream 1630 emerging from the firstseparation system 1620 passes into a second separation system 1624,which separates hydrogen from the fluid stream. Hydrogen can be recycled1638 into the plasma-based hydrocarbon processor 1602 for furtherreactions therein. The hydrogen separation system 1624 also produces aconcentrated effluent stream 1640 that contains acetylene, which canthen be reacted with hydrogen chloride gas 1626 within the VCM reactor1606 to yield VCM. The VCM-containing gas stream, the VCM reactoreffluent 1628, then enters the third separation system 1622, whichcondenses the VCM from the VCM reactor effluent 1628 through a series ofcomponents substantially similar to those described in FIG. 15A. In moredetail, this third separation system 1622 comprises a compressor 1622 ato compress the VCM reactor effluent 1628 and a chiller 1622 b thatlowers the temperature of the VCM reactor effluent 1628, allowing theVCM to condense out of the VCM effluent as a liquid, which can then beremoved from the fluid stream by the liquid-gas separator 1622 c as aseparate liquid VCM product 1636. The chiller 1622 b can be operated bycirculating refrigerant 1622 d or any other mechanism familiar toartisans of ordinary skill. The stream of residual gas 1632 that emergesfrom the liquid-gas separator 1622 c contains mainly hydrogen, and theresidual gas stream 1632 can then be discarded or further processedthrough a hydrogen separator (either by routing it (not shown) to thehydrogen separator 1624 previously described, or another hydrogenseparator not shown).

FIG. 15A and FIG. 16 each depicts a VCM reactor (1506, 1606) thatconverts acetylene and hydrogen chloride gas into VCM. An embodiment ofan exemplary VCM reactor for use with the aforesaid systems and methodsfor VCM manufacture is shown in more detail in FIG. 17 . The VCM reactor1700 comprises an external housing 1702 within which is supported acatalytic bed, which in the depicted embodiment is formed from aplurality of catalyst-containing cylindrical tubes 1704. The housing canbe made of stainless steel or any other suitable substance, as is knownin the art. The catalyst-containing tubes 1704 can be made of glass orany other suitable substance as is known in the art. A plurality ofcatalyst pellets are deployed within the catalyst-containing tubes 1704to form a packed bed 1708. Each of the catalyst pellets 1710 comprises asupport 1710 a attached to which or in proximity to which are aplurality of catalyst particles 1710 b; the support 1710 a is configuredwith pores 1710 c through at least some of which the purified effluentstream containing acetylene passes to contact the catalyst particles,thereby increasing the surface area across which the reactants cancontact the catalyst particles 1710 b. Reactants 1712 (acetylene and HClgas) enter a proximal end 1714 of the catalyst-containing tubes 1704,and pass through the tubes 1704 distally to their distal end 1718. Asthe reactants 1712 pass through the tubes 1704, they contact thecatalyst particles therein and undergo a catalytic reaction to form thedesired product VCM 1720. The VCM 1720 emerges from the distal end 1718of the catalyst-containing tubes 1704. An elevated reaction temperaturemay be desirable, in which case heated oil or any other heated substancecan be circulated within the reactor to surround the catalyst-containingtubes 1704. In the depicted embodiment, hot oil 1728 enters at an inlet1722 located on a distal portion of the reactor housing 1702, and itexits at an outlet 1724 located on a proximal portion of the reactorhousing 1702. In embodiments, a hot oil temperature between 150 and 220°C. is advantageous. Other temperatures can be maintained by varying thetemperature of the circulating heating substance or cooling substance asappropriate. Other modifications of reactor design can be substitutedfor this example without departing from the spirit and scope of thedisclosed invention, as would be understood by those of ordinary skillin the art.

Catalysts suitable for use with the VCM reactor system described hereinare familiar in the art and can be prepared by individuals with ordinaryskill by following published procedures, such as those set forth in thefollowing references, whose contents are incorporated herein byreference. Examples of catalysts suitable for use with these systems andmethods include, without limitation: HgCl₂ on activated carbon(disclosed, for example, in U.S. Pat. 2446123); Au₂(S₂O₃)₃ on activatedcarbon (disclosed, for example, in Patent US9409161), HAuCl₄ onactivated carbon (disclosed, for example, in J. Catal., 2013, 297,128-136); AuCl₃ on mesoporous carbon material (disclosed, for example,in Catal. Sci. Technol., 2015, 5, 1035-1040) HAuCl₄, H2PtCl₆, RhCl₃,IrCl₃, and/or PdCl₂ on activated carbon (disclosed, for example, in J.Catal., 2008, 257, 190-198); CuCl₂ and BiCl₃ on silica gel (disclosed,for example, in Fuel Process. Technol., 2013, 108, 12-18); (PPh₃)AuCl onactivated carbon (disclosed, for example, in Catal. Sci. Technolog.,2016, 6, 7946-7955), RuCl₃ on activated carbon (disclosed, for example,in RSC Adv., 2017, 7, 23742-23750). Bimetallic catalytic systems foracetylene hydrochlorination are also suitable for use with the VCMreactor system described herein, including AuCl, AuLa, AuBa, AuNi, AuCs,AuTiO₂, and AuCoCu; descriptions of suitable bimetallic catalyst systemscan be found in ACS Catal., 2015, 5, 5306-5316.

B. Vitamins A and E Manufacturing

As another example, the acetylene and hydrogen produced by theplasma-based hydrocarbon processing system can act as the precursor forother industrial processes, such as the manufacturing of Vitamins A andE and their respective chemical intermediates. A plasma-basedhydrocarbon processing system as described above can be modified so thatit maximizes and optimizes the acetylene produced, and it can beintegrated with those processes required to convert the acetylene intothese vitamin products. In addition, such a system can produce hydrogen,which can be used in manufacturing vitamin products.

In embodiments, a plasma-based hydrocarbon processing system forproducing acetylene and hydrogen, as described above, can deliver eitherof these products into subsystems for further processing, so that afully integrated industrial application is constructed that incorporatesprecursor production (i.e., acetylene and/or hydrogen produced by theplasma-based hydrocarbon processing system) and precursor utilization toform industrially useful products. For example, the acetylene producedby the plasma-based hydrocarbon processing system can act as theprecursor for other industrial processes, such as the manufacture ofVitamins A and E, provitamin beta-carotene, and their respectivechemical intermediates. Acetylene, along with C₃-feedstock (e.g.,Acetone, diketene, ethyl acetoacetate, isopropenyl methyl ether) andhydrogen, is a vital raw material for the commercial productions ofvitamins A and E, and provitamin β-Carotene (collectively, “vitaminproducts”). A plasma-based hydrocarbon processing system as describedabove can be modified so that it maximizes and optimizes the acetyleneproduced, and it can be integrated with those processes required toconvert the acetylene into these products.

A representative multistep synthetic pathway showing the chemicalintermediates useful for the manufacture of Vitamins A and E and theprovitamin beta-carotene is set forth in FIG. 18 . From an overall massbalance perspective, 1 kg of vitamin products consists of 0.25 kg C₂H₂in Vitamin E, and 0.27 kg C₂H₂ in Vitamin A, and 0.29 kg C₂H₂ inβ-Carotene. The synthetic paths 1800 shown in FIG. 18 permit thesynthesis of vitamin products using acetylene as the main hydrocarboningredient. As shown in FIG. 18 , a common initial pathway (1800 a,comprising Steps 1802, 1804, 1808) produces the common precursordehydrolinalool, which is then transformed into Vitamin E via pathway1800 b (comprising Steps 1810, 1812, 1814, 1818, 1820 and 1822), orwhich is then transformed into Vitamin A through pathway 1800 c(comprising Step 1824, or alternatively Steps 1830 and 1832, then Steps1828, 1838, and 1840; Step 1834 shows the pathway by which a precursorfor step 1838 is formed). As used herein, the term “Vitamin A” refers toand includes the four main forms of Vitamin A: retinal, retinol,retinoic acid, and retinol-esters (e.g., retinol acetate). Forsimplicity, the structure of Vitamin A is depicted as retinol in FIGS.18, 19 and Table 5 (below). Beta-carotene is formed from Vitamin A asrepresented schematically in Step 1840.

In the first step of the common initial pathway 1800 a (Step 1802),there are two separated reaction sequences to this step: ethynylationand hydrogenation. The former involves reacting acetone with acetylenein the presence of a base/solvent combination (as described below). Inthis step, acetylene’s terminal hydrogen atom is deprotonated by thebase, allowing the acetylide to attach to the carbonyl of the acetone.The second sequence following ethynylation, as depicted in this Figure,is hydrogenation by Lindlar catalyst that hydrogenates the alkyne toalkene moiety. Overall, step 1802 produces 2-methylbut-3-en-2-ol, whichin Step 1804 reacts with isopropenyl methyl ether to form6-methylhept-5-en-2-one. In Step 1808, acetylene is reacted with6-methylhept-5-en-2-one (from Step 1804) to produce dehydrolinalool, thecommon precursor for Pathways 1800 b and 1800 c. For convenience, namesof reagents, intermediates, and products shown in FIG. 18 are set forthin Table 5. Note, chemical structures shown in FIGS. 18, 19 and Table 5do not refer to a specific E/Z and R/S stereoisomer configuration fortheir respective chemicals’ names. For simplicity, only a singlestereoisomer structure is shown in the figures and tables. Moreover, thechemicals names used herein are understood by artisans of ordinary skillto refer to all possible stereoisomers, including, but not limited to, asingle stereoisomer, a non-racemic mixture of stereoisomers, and aracemic mixture of stereoisomers of the same compound.

TABLE 5 Structure / Formula Name(s)

• Acetone • Propan-2-one

• Acetylene • Ethyne

• But-3-en-2-one

• 2-methylbut-3-en-2-ol

• 3-methylpent-2-en-4-yne-1-ol

• Isopropenyl methyl ether • 2-methyoxyprop-1-ene

• 6-methylhept-5-en-2-one

• Dehydrolinalool • 3,7-dimethyloct-6-en-1-yn-3-ol

• Linalool • 3,7-dimethylocta-1,6-dien-3-ol

• 6,10-dimethylundeca-5,9-dien-2-one

• 3,7,11-trimethyldodeca-1,6,10-trien-3-ol

• 6,10,14-trimethylpentadeca-5,9, 13-trien-2-one

• 3,7,11,15-tetramethylhexadec-1-en-3-ol

• Vitamin E •2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)chroman-6-ol

• Pseudoionone • 6,10-dimethylundeca-3,5,9-trien-2-one

• Citral • 3,7-dimethylocta-2,6-dienal

• β-ionone • 4-(2,6,6-trimethylcyclohex-1-en-1-yl)but-3 -en-2-one

• Vitamin A •3,7-dimethyl-9-(2,6,6-trimethylcyclohex-1-en-1-yl)nona-2,4,6,7-tetraenal

• β-Carotene •2,2′-(3,7,12,16-tetramethyloctadeca-1,3,5,7,9,11,13,15,17-nonaene-1,18-diyl)bis(1,3,3-trimethylcyclohex-1-ene)

Following Pathway 1800 b results in the formation of Vitamin E throughSteps 1810, 1812, 1814, 1818, 1820, and 1822. In more detail, Step 1810hydrogenates dehydrolinalool in the presence of a Lindlar catalyst toform linalool. Step 1812 combines linalool with isopropenyl methyl etherto form 6,10-dimethylundeca-5,9-dien-2-one. In Step 1814, this productis first reacted with acetylene, and then catalytically hydrogenated, toproduce 3,7,11-trimethyldodeca-1,6,10-trien-3-ol. This product is thenreacted with 2-methoxy-1-propene (Step 1818), to form a product that isreacted with acetylene and then catalytically hydrogenated (Step 1820)to form 3,7,11,15-tetramethylhexadec-1-en-3-ol, which is converted viaStep 1822 via a catalyzed Friedel-Craft alkylation to form Vitamin E,for example, following those procedures set forth in CHIMIA 2014, 68,485-491, the contents of which are included herein by reference. Pathway1800 c results in the formation of Vitamin A, through Steps 1824 (oralternate Steps 1830 and 1832) through Steps 1828 and 1838. Either Step1824 or Steps 1830 and 1832 result in the formation of pseudoionone,which can then be converted into beta-ionone by acidification, as shownin Step 1828. To form pseudoionone in Step 1824, isopropenyl methylether is added to dehydrolinalool. Alternatively, pseudoionone is formedthrough Steps 1830 and 1832, by first converting dehydrolinalool tocitral using a vanadium catalyst through an internal rearrangementprocess, and then combining citral with acetone to produce pseudoionone.Pseudoionone can then be converted into beta-ionone by acidification inStep 1828. Once beta-ionone is formed, it can be combined with3-methylpent-2-en-4-yn-1-ol (formed from acetylene and methyl vinylketone in step 1834) to yield Vitamin A. Vitamin A, in turn, can be usedas a precursor for other molecules, for example, Beta-carotene,represented schematically by Step 1840.

Underpinning the complex synthetic pathway for vitamins/provitamins asshown in FIG. 18 are controlled ethynylation reactions where acetyleneselectively adds methyl ketone groups. These reactions proceed by asingular deprotonation of acetylene’s C—H bonds by a strong basefollowed by addition of a ketone electrophile (e.g., acetone) resultingin a C—C bond formation, as illustrated by the following formula:

In many cases, only a catalytic amount of base is needed to be added tothe reactor to effect the necessary deprotonation. In commercialapplications, potassium hydroxide and liquid ammonia is the preferredbase/solvent combo, as illustrated above. Other base/solvent combinationthat can be used for ethynylation reactions include but limited topotassium hydroxide / dimethyl sulfoxide, sodium / methanol, potassiumhydride / tetrahydrofuran, and sodium amide / diethyl ether. Thebase-mediated reaction occurs once per acetylene molecule, preventingover-alkylation of the acetylene. This simple stepwise reaction isrepeated numerous times in an ethynylation, hydrogenation, andcondensation reaction sequence as depicted in FIG. 18 to construct thelong terpenoid structures that form the backbone of the final vitaminproducts. These ethynylation reactions can be performed in batch-wise orsemi-continuously, typically using sodium hydroxide in ammonia todeprotonate acetylene, which operates catalytically, reducing the amountof base required.

FIG. 19 depicts a multistep synthesis 1900 that is identical to thatshown in FIG. 18 , with certain details in pathways 1900 a, 1900 b, and1900 c highlighted for clarity. In this Figure, dashed boxes are placedwithin the structures in the reactions to show those carbon atomscontributed by acetylene to synthetic intermediaries and final products,and solid boxes are placed around the acetylene molecules themselves.The illustrations in FIG. 19 demonstrate schematically the centrality ofacetylene to the synthesis of vitamin products. In FIG. 19 , theincorporation of acetylene is seen in Steps 1902, 1908, 1914, 1920, and1934. Acetylene for each of these steps can be provided by aplasma-based hydrocarbon processing system, as described herein.

An illustrative example of such a plasma-based hydrocarbon processingsystem that would be useful for producing acetylene and hydrogen forvitamin manufacturing has been previously described in conjunction withFIG. 9 . As previously shown in FIG. 9 above and described in moredetail herein, the inflow gas streams 912 and 914 are processed in thereactor 902 to form an outflow stream 918 that contains acetylene,hydrogen, and a small proportion of mixed hydrocarbons. The outflowstream 918 is then separated into its gaseous components via a gasseparation system 928 (e.g., adsorption, absorption, or a combinationthereof) to yield an acetylene stream 920 and a hydrogen-dominant gasstream 922 that contains hydrogen 936 and a mixture of hydrocarbons 924.Thus diverted from the main outflow stream 918 by the gas separationsystem 928, the acetylene stream 920 can be purified via furthersequestration of impurities in a purification system 926 to yield apurified acetylene gas product 932. The purified acetylene gas product932 is available for use in further industrial processes, such as thesynthesis of vitamin products depicted in FIGS. 18 and 19 .

Using the systems and methods disclosed herein, acetylene and hydrogencan be produced on-site from natural gas or other hydrocarbon rawmaterials to be used for vitamin and provitamin manufacturing. Thesesystems and methods can allow vitamin manufacturers to control their ownacetylene production capacity and rates of resource utilization whileproviding an acetylene source of high purity.

FIG. 20 depicts a general scheme showing the steps of the process forproducing vitamin products 2000, using acetylene and hydrogen producedby a plasma-based hydrocarbon processing system as has been disclosedherein. Note that the scheme shown in FIG. 20 can take advantage of avariety of plasma-based hydrocarbon processing systems such as have beendisclosed herein, whereby acetylene and/or hydrogen is produced usingsuch a system, and whereby the gas(es) so produced are then used, inwhole or in part, for producing vitamin products. Pathway 2002 a showsthe steps for producing acetylene from raw materials in accordance withthese systems and methods. As an initial step, raw materials areprovided 2004 for further processing, wherein the raw materials comprisea hydrocarbon-containing inflow gas, and can further comprise a recycledgas. The raw materials are then processed 2008 into outflow gas productscomprising acetylene, hydrogen, and acetylene byproducts in a reactorhaving a gas delivery subsystem, a plasma reaction chamber, and amicrowave subsystem, as described previously, with the acetylene,hydrogen, and byproducts exiting the reactor to enter a set ofseparators for further separation and purification steps 2010. Inembodiments, the step of processing 2008 comprises the steps (not shown)of injecting the hydrocarbon-containing inflow gas into the plasmareaction chamber; energizing the hydrocarbon-containing inflow gas inthe plasma reaction chamber with microwave energy to create a plasma;forming outflow gas products in the plasma, wherein the outflow gasproducts comprise acetylene and hydrogen; flowing the outflow gasproducts to exit the plasma reaction chamber, whereupon the outflow gasproducts are processed with a set of separation and purification steps2010. The separation and purification steps 2010, comprising the stepsof effluent separation, acetylene separation, and hydrogen separation,yield a set of component gases comprising a pure acetylene product 2012,which pure acetylene product 2012 then is distributed 2016 so that itenters a process for vitamin manufacturing 2018. The separation andpurification steps also produce off-gases 2014 such as acetylenebyproducts and pure hydrogen that are removed or isolated from the pureacetylene product 2012.

As mentioned above, the pure acetylene product 2012 produced by theseparation and purification steps 2010 is distributed 2016 for furtheruse in vitamin manufacture 2018. The pure acetylene can be distributed2016 for this purpose via direct delivery 2024 (i.e., without anyintermediate diversions or sequestrations of gas); in addition, the pureacetylene product 2012 can be distributed 2016 for storage 2022, or fora commercialization process 2020 such as bottling, with either of thesedestinations available to be subsequently used for vitamin manufacturing2018 (as shown in paths 2026 and 2028). The distribution process 2016 isintended to optimize the utilization of the acetylene produced by theplasma-based hydrocarbon processing pathway 2002 a by adjusting theinflow of the acetylene 2012 produced though this pathway 2002 a toconform to the needs of the process for vitamin manufacturing 2018, forexample, via a feedback mechanism whereby the inflow of the acetylene2012 is increased or decreased depending on a measurement for requisiteacetylene provided by the vitamin manufacturing system. The steps shownby the pathways within 2002 b illustrate ways by which pure acetylene2012 produced by the plasma-based hydrocarbon processing pathway 2002 acan enter the synthetic process for manufacturing vitamin products 2018.One option involves acetylene bottling 2020, wherein the pure acetylene2012 is bottled in a compressed form and delivered 2026 to themanufacturing plant for subsequent use in producing vitamin products2018. Acetylene bottling 2020, familiar in the art, is well known tohave commercially important drawbacks however, including safety concernsand logistical difficulties. A second option involves the storage of theacetylene in a gas holding tank 2022 at near atmospheric pressure, withsubsequent delivery 2028 for vitamin manufacture 2018. While thisapproach offers advantages compared to acetylene bottling 2020, safetyconcerns and logistical difficulties still exist. Direct delivery 2024of pure acetylene 2012 for vitamin manufacture 2018 is a highlydesirable option. Using the systems and methods disclosed herein andillustrated in the Figure to follow, a predictable source of highlypurified acetylene 2012 can be provided for use in vitamin manufacture2018, desirably via direct delivery 2024 into vitamin manufacturingprocesses 2018.

FIG. 21 shows in more detail how the systems and methods disclosedherein can be integrated with systems and processes for manufacturingvitamin products. In embodiments, this Figure illustrates how thesystems and methods disclosed herein efficiently produce a highlypurified acetylene that is suitable for direct and/or controllabledelivery to the manufacturing processes, and how the systems and methodsdisclosed herein can optimize delivery of acetylene to vitaminmanufacturing systems and processes in keeping with the variable demandsof these processes, while minimizing the need for ancillary storagefacilities.

FIG. 21 shows an embodiment of an integrated acetylene-based vitaminsynthesis system 2100 in which a plasma-based hydrocarbon processingsystem 2102 as described herein interfaces with a system 2150 formanufacturing vitamin products 2106, for example, the vitamin productsor precursors thereof shown in the synthetic diagrams in FIGS. 18 and 19. In the depicted embodiment, the vitamin manufacturing system 2150comprises a vitamin reaction plant 2104, a controlling system (or“controller”) 2116, an acetylene receptacle 2142, and a hydrogenreceptacle 2144. In the depicted embodiment: (i) the reactions describedin FIG. 18 and FIG. 19 for manufacturing of vitamin products 2106 arecarried out by suitable reactors (not shown) within the vitamin reactionplant 2104; (ii) the acetylene receptacle 2142 and the hydrogenreceptacle 2144 are available to store acetylene and hydrogen gases thatare produced by the plasma-based hydrocarbon processing system 2102 orthat are obtained from other sources; and (iii) the controller 2116controls the flow of acetylene and hydrogen from the plasma-basedhydrocarbon processing system 2102 into the vitamin reaction plant 2104and/or the receptacles 2142 and 2144 as needed. While the depictedembodiment includes the receptacles 2142 and 2144, it is understood thatthe plasma-based hydrocarbon processing system 2012 as disclosed hereincan also provide acetylene and/or hydrogen for direct delivery asdescribed above, without a need for receptacles or other containers forstoring excess gas. In such an embodiment, the controller 2116 controlsthe flow of acetylene and hydrogen from the plasma-based hydrocarbonprocessing system 2102, for example, from the acetylene and hydrogenseparators, respectively, into the vitamin reaction plant 2104 withoutintermediate diversions or sequestrations of gas(es). It is furtherunderstood that other arrangements or components for the vitaminmanufacturing system 2150 can be envisioned by skilled artisans asembodiments of an integrated acetylene-based vitamin synthesis system2100 employing the plasma-based hydrocarbon processing system 2102 asdescribed herein.

In more detail with reference to FIG. 21 , the plasma-based hydrocarbonprocessing system 2102 yields a highly purified acetylene product 2108that can be delivered into the system 2150 for manufacturing vitaminproducts 2106. In the depicted embodiment, the plasma-based hydrocarbonprocessing system 2102 comprises a hydrocarbon inflow stream 2110 (e.g.,natural gas) and a recycled gas stream 2112, a microwave reactor 2114comprising a plasma reaction chamber (not shown) into which thehydrocarbon inflow stream 2110 and the recycled gas stream 2112 aredelivered, wherein they are energized by a microwave subsystem (notshown) to form a plasma that yields chemical products that emerge fromthe plasma chamber to form an outflow stream 2118 of outflow gasproducts, all as have been described above in detail. In the depictedembodiment, the outflow stream 2118 is subjected to further processingand separation, including passage through a set of separator subsystems.

The set of separator subsystems, all of which have been describedpreviously in more detail, include: (i) an effluent separator 2120 forthe removal of higher acetylenes and aromatic impurities (C₃ ⁺) (usingfor example, a temperature swing adsorber or a prescrubber), yielding apurified effluent stream 2122; (ii) an acetylene separator 2124 for theseparation of the highly purified acetylene product 2108 from thepurified effluent stream 2122 via acetylene purification columns or thelike, to yield a remaining effluent stream 2128; and (iii) a hydrogenseparator 2130 (e.g., a pressure swing absorber or a membraneseparator).

The embodiment shown in FIG. 21 provides one sequencing of the separatorsteps and subsystems. In the depicted embodiment, the remaining effluentstream 2128 divides into two streams, 2128 a and 2128 b. The firstremaining effluent stream 2128 a undergoes further treatment in thehydrogen separator 2130, with the purified hydrogen product 2132 beingseparated therefrom. The other remaining effluent stream 2128 b isdiverted before entering the hydrogen separator 2130 and instead isrecycled, forming a recycled gas stream 2112 (either alone or, asdepicted, in conjunction with other gas streams such as the residual gasstream 2136 exiting the hydrogen separator 2130), with the recycled gasstream 2112 being available for use in the microwave reactor 2114 asdescribed previously. The residual gas stream 2136 can be used to formthe recycled gas stream 2112, either blended with other recyclable gasstreams such as the remaining effluent stream 2128 b (as depicted inthis Figure) and/or combined with other gas streams (not shown), or usedalone to form the recycled gas stream 2112.

Purified hydrogen product 2132 can be directed in a dedicated hydrogenstream 2132 a for ultimate use in the vitamin reaction plant 2104;alternatively, purified hydrogen product 2132 can be directed away fromthe vitamin manufacturing system 2150 in an external hydrogen stream2132 b for separate sale, storage, or disposal. In more detail, thepurified hydrogen product 2132 a can be directed by the controller 2116to a holding tank or other receptacle 2144 for use in the vitaminreaction plant 2104. The receptacle 2144 can be configured as a holdingtank for temporary storage, wherein the purified hydrogen 2132 d residesfor a preselected period of time based on the needs of the overallvitamin manufacturing system 2150. Similarly, the purified acetyleneproduct 2108 can be directed in a dedicated acetylene stream 2108 a foruse in the vitamin reaction plant 2104; alternatively, purifiedacetylene product 2108 can be directed away from the vitaminmanufacturing system 2150 in an external acetylene stream 2108 b forseparate sale, storage, or disposal. In more detail, the purifiedacetylene product 2108 a can be directed to a holding tank or otherreceptacle 2142 for use in the system for manufacturing vitaminproducts. The receptacle 2142 can be configured as a holding tank fortemporary storage, wherein the purified acetylene 2108 d resides for apreselected period of time based on the needs of the overall vitaminmanufacturing system 2150.

In embodiments, a controller 2116 is positioned to receive acetylene andhydrogen from (respectively) the dedicated acetylene stream 2108 a andthe dedicated hydrogen stream 2132 a, and to deploy these reactants foruse in the vitamin manufacturing system 2150. As shown in the schematic,the controller 2116 can pass the purified acetylene 2108 into thevitamin reactor plant 2104 via an acetylene inflow stream 2108 c,wherein the acetylene inflow stream 2108 c contains the purifiedacetylene product 2108 produced by the plasma-based hydrocarbonprocessing system 2102. In addition or alternatively, the controller2116 can divert some or all of the purified acetylene 2108 into thereceptacle 2142 for temporary storage via a storage circuit 2108 d, andthe controller can direct the release of purified acetylene from thereceptacle 2142 via the storage circuit 2108 d so that it enters theacetylene inflow stream 2108 c for use in the vitamin reactor plant 2104to produce vitamin products 2106. Similarly, as shown in the schematic,the controller 2116 can pass the purified hydrogen 2132 into the vitaminmanufacturing system 2104 via a hydrogen inflow stream 2132 c, whereinthe hydrogen inflow stream 2132 c contains the purified hydrogen product2132 produced by the plasma-based hydrocarbon processing system 2102.Additionally or alternatively, the controller 2116 can divert some orall of the purified hydrogen 2132 into a receptacle 2144 for temporarystorage via a storage circuit 2132 d, and the controller can direct therelease of purified hydrogen from the receptacle 2144 via the storagecircuit 2132 d so that it enters the hydrogen inflow stream 2132 c foruse in the vitamin reactor plant 2104 to produce vitamin products 2106.Each receptacle 2142 and 2144 can further be in fluid communication withthe external stream for its respective gas contents (for acetylene, 2108b, and for hydrogen 2132 b), via an offload conduit (shown as the dashedline 2146 for acetylene and the dotted line 2148 for hydrogen).

Purified acetylene 2108 that is stored in the receptacle 2142 can bedissolved in a solvent within the receptacle 2142, for example, solventssuch as N-methyl pyrrolidone, and dimethylformamide, and/or liquidammonia. In embodiments, the acetylene gas 2108 d directed to thereceptacle 2142 is compressed before reaching the receptacle 2142 via acompressor (not shown), so that the receptacle 2142 can providesufficient storage for the manufacturing facility’s needs in a smallerspace. In embodiments, the acetylene gas 2108 d can be compressed via acompressor (not shown) into the receptacle 2142 along with an inertcarrier gas or a non-inert gas such as gaseous ammonia, or the acetylenegas 2108 d can be compressed into the inert carrier gas or non-inert gassuch as gaseous ammonia that is already contained in the receptacle2142. In embodiments, the acetylene 2108 a can be directed by thecontroller 2116 to bypass the receptacle 2142 and be directed as adirect delivery distribution via the acetylene inflow stream 2108 c intothe vitamin reactor plant 2104; in other embodiments, the acetylene 2108needed for various steps of vitamin synthesis is obtained from theacetylene stored in the receptacle 2142, with said acetylene beingdirected by the controller 2116 from the receptacle 2142 into thevitamin reactor plant 2104 via the acetylene inflow stream 2108 c, ascontrolled by the controller 2116. It is understood that the controller2116 can control the inflow 2108 c of acetylene for vitamin manufacturethat is provided from any available source, including any combination ofthe plasma-based hydrocarbon processing system 2102, the acetylenereceptacle 2142, and any other source (not shown) providing acetylene ofappropriate purity for vitamin manufacture. A similar set of options isavailable for hydrogen, so that the hydrogen 2132 a can be directed bythe controller 2116 to bypass the receptacle 2144 and be directed as adirect delivery distribution via the hydrogen inflow stream 2132 c intothe vitamin reactor plant 2104; in other embodiments, the hydrogen 2132needed for various steps of vitamin synthesis is obtained from thehydrogen stored in the receptacle 2144, with said hydrogen beingdirected by the controller 2116 from the receptacle 2144 into thevitamin reactor plant 2104 via the hydrogen inflow stream 2132 c, ascontrolled by the controller 2116. It is understood that the controller2116 can control the inflow 2132 c of hydrogen for vitamin manufacturefrom any available source, including any combination of the plasma-basedhydrocarbon processing system 2102, the hydrogen receptacle 2144, andany other source (not shown) providing hydrogen of appropriate purityfor vitamin manufacture.

In embodiments, the controller 2116 contains a feedback loop or similarprocessing system(s) that modulate the rate of processes carried out bythe plasma-based hydrocarbon processing system 2102 in order to allowfor just-in-time production of purified acetylene 2108 or hydrogen 2132as required by the vitamin manufacturing system 2104; for example, inembodiments, the controller 2116 permits intermittent production ofpurified acetylene 2108 or hydrogen 2132, or controls the rate of theirproduction or controls their diversion outside the system, for example,into external streams for acetylene 2108 b or hydrogen gas 2132 b. Inembodiments, the controller 2116 can regulate the amount of hydrogenthat is extracted by the hydrogen separator 2130 from the remainingeffluent stream 2128 a, and/or the controller can regulate the volume ofthe remaining effluent stream 2128 that is diverted 2128 b to comprisethe recycled gas stream 2112. Other interfaces between the controller2116 and the plasma-based hydrocarbon processing system 2102 can beenvisioned by skilled artisans in order to synchronize the needs of thevitamin reactor plant 2104 with the output from the plasma-basedhydrocarbon processing system 2102.

As further exemplification, in embodiments, a number of variations tothe system 2100 can be implemented in order to allow for intermittentproduction, just-in-time production, or interrupted production ofacetylene and/or hydrogen for vitamin manufacturing. As shown in FIG. 21, the hydrocarbon inflow stream 2110 is energized in the microwavereactor 2114 along with the recycle gas 2112, producing acetylene andhydrogen in the outflow stream 2118. As shown, the outflow stream 2118is further processed to provide purified acetylene 2108 for the vitaminmanufacturing system 2150. If it is necessary to stop production ofacetylene and hydrogen, for example, if throughput of the gas(es) is notrequired for vitamin manufacture and/or sufficient gas(es) have beenprovided for vitamin manufacture and capacity of the receptacles 2142and/or 2144 is not adequate for storing the excess gases, the microwavereactor 2114 can be powered down to stop the production of acetylene andhydrogen, including as applicable shutting off the delivery ofhydrocarbon-containing inflow gas 2110. Following such a shutdown, therecycle gas 2112 can be simply recirculated (not shown) within thesystem 2102. In other embodiments, the recycle gas 2112 that isrecirculated can also bypass one or more purifications steps (e.g.,2120, 2124, and 2130) if needed. In a preferred embodiment, therecirculating recycle gas bypasses 2124 and 2130, and the exiting gases(2128 and 2108) from the acetylene purification columns 2124 arere-circulated to re-enter the acetylene purification columns 2124. Gasflow pathways and operating conditions to dissociate the plasma-basedhydrocarbon processing system 2102 from the vitamin manufacturing system2150 can be coordinated based on the vitamin manufacturing system’sneeds or on other preselected parameters.

In embodiments, the controller 2116 accomplishes this coordination. Theinteraction of the components of the integrated acetylene-based vitaminsynthesis system 2100 as mediated by the controller 2116 allows thesupply side of the system (i.e., the plasma-based hydrocarbon processingsystem 2102) to respond quickly to the requirements from the demand sideof the system (i.e., the vitamin manufacturing system 2150), forexample, rapidly changing the volume of acetylene produced, orstarting/stopping the production and delivery of acetylene and hydrogento the vitamin reactor plant 2104 as needed, or diverting more or lessof the hydrogen-containing remaining effluent stream 2128 for recycling2112.

Steps for the manufacture of Vitamins A and E and their precursors arefamiliar to artists of ordinary skill in the art, with the plasma-basedhydrocarbon processing system 2102 as described herein providing some orall of the acetylene and/or hydrogen used in those manufacturingprocesses. Therefore, the synthetic processes for the manufacture ofvitamin products 2106 that have been described previously in FIGS. 18and 19 are not depicted in FIG. 21 . However, as an example of how thesystems of FIG. 21 can perform the synthetic processes of FIGS. 18 and19 , a series of reactors (not shown) can be disposed within the vitaminreactor plant 2104 and can be charged with appropriate reagents to carryout the reactions as shown in FIG. 18 and FIG. 19 , as would beunderstood by artisans of ordinary skill. The acetylene and hydrogen tobe delivered into those reactors can be preliminarily compressed (notshown) as necessary. In embodiments, reaction paths can be providedwithin the vitamin manufacturing system 2150 to provide acetylene and/orhydrogen for one or more of the depicted reactions as shown in FIG. 18and FIG. 19 , for example, ethynylation reactions and hydrogenationreactions as required by the steps in the synthetic pathways, withisolation of reaction products and further ethynylation and/orhydrogenation thereof in accordance with the steps in the syntheticpathways.

While FIG. 20 and FIG. 21 show a particular order of the separatorsubsystems, it is understood that, in other embodiments, the orderedposition of the effluent separator, the acetylene separator, and thehydrogen separator can be rearranged. FIG. 22 shows one arrangement ofthese components. As illustrated in FIG. 22 , inflow 2206 from theplasma-based hydrocarbon processing system 2200 described above firstenters (i) an effluent separator 2202 for removal of higher acetylenesand aromatic impurities 2204 (collectively forming Block A in theFigure) as described above, forming an effluent stream 2216 withouthigher acetylenes and aromatic impurities. The effluent separator 2202is in fluid communication with (ii) an acetylene separator 2208, whichreceives the effluent stream 2216 and removes a purified acetyleneproduct 2210 therefrom (collectively forming Block B in the Figure) asdescribed above. The acetylene separator 2208 in turn is in fluidcommunication with (iii) a hydrogen separator 2212 for removal of apurified hydrogen product 2214 (collectively forming Block C in theFigure), with any residual gas depicted as remaining gas 2218. Asdepicted, remaining gas 2218 can be recycled for further use in theplasma-based hydrocarbon processing system 2206. This arrangement hasbeen described above and illustrated in FIGS. 20 and 21 . As has beenpreviously described, the purified hydrogen product 2210 and thepurified acetylene product 2214 are suitable for use in the vitaminmanufacturing system 2220. Other arrangements of the depicted blocks arealso compatible with the systems and methods disclosed herein. Inembodiments, for example: Block A (C⁺ separation) can precede Block C(H₂ separation), which precedes Block B (C₂H₂ separation); Block C (H₂separation) can precede Block A (C⁺ separation), which precedes Block B(C₂H₂ separation); or Block C (H₂ separation) can precede Block B (C₂H₂separation), which is followed by Block A (C⁺ separation), with anyrecycling based on the ordering of the blocks. In embodiments, one ormore of the Blocks can be omitted. For example, if pure hydrogen isprovided into the system from an external source, hydrogen separation(Block C) can be omitted. Or, for example, a vitamin manufacturingsystem can have a lower purity requirement than is provided by thesesystems and methods, in which case Block A (C⁺ separation) can beomitted. In other embodiments, hydrogen can be provided from an externalsource to the vitamin manufacturing system and a lower purity foracetylene is satisfactory for use; in this case, only Block B (C₂H₂separation) is required.

c. Acetylene Decomposition

As another example, the acetylene produced by the plasma-basedhydrocarbon processing system can be used as a precursor for acetylenedecomposition processes, which yield hydrogen gas and acetylene black. Aplasma-based hydrocarbon processing system as described above can bemodified so that it maximizes and optimizes the acetylene produced, andthe system can be integrated with processes required to convert theacetylene into hydrogen gas and acetylene black. In embodiments, aplasma-based hydrocarbon processing system for producing acetylene, asdescribed above, can deliver this product as a feedstock into anacetylene decomposition subsystem for further processing, so that afully integrated industrial application is constructed that incorporatesprecursor production (i.e., acetylene produced by the plasma-basedhydrocarbon processing system) and precursor utilization to form thedesired product, which can be either acetylene black or hydrogen, withthe simultaneous production of either hydrogen gas or acetylene black(respectively) as a useful byproduct. Using the systems and methodsdisclosed herein, acetylene can be produced on-site from natural gas orother hydrocarbon raw materials to be used for acetylene decomposition,with production of acetylene black and hydrogen. These systems andmethods can allow manufacturers to control their logistics and rates ofresource utilization by taking advantage of an integrated acetylenesource of high purity.

FIG. 23 provides a block diagram showing a general scheme with a seriesof steps for the process 2300 for producing acetylene black andhydrogen, using the acetylene produced by the plasma-based hydrocarbonprocessing system that has been disclosed herein. Note that the schemeshown in FIG. 23 can take advantage of a variety of plasma-basedhydrocarbon processing systems such as have been disclosed herein,whereby acetylene is produced using such a system, and whereby the gasso produced is then used, in whole or in part, for producing acetyleneblack and/or hydrogen.

Pathway 2302 a shows the steps for producing acetylene from rawmaterials using a plasma-based hydrocarbon processing system aspreviously disclosed. As an initial step in the process 2300, rawmaterials are provided 2304 for further processing, wherein the rawmaterials comprise a hydrocarbon-containing inflow gas, and can furthercomprise a recycled gas. The raw materials are then processed 2308 intooutflow gas products comprising acetylene, hydrogen, and acetylenebyproducts using a reactor having a gas delivery subsystem, a plasmareaction chamber, and a microwave subsystem, as described previously,with the acetylene, hydrogen, and byproducts exiting the reactor toenter a set of separators for further separation and purification steps2310. In embodiments, the step of processing 2308 comprises the steps(not shown) of injecting the hydrocarbon-containing inflow gas into theplasma reaction chamber; energizing the hydrocarbon-containing inflowgas in the plasma reaction chamber with microwave energy to create aplasma; forming outflow gas products in the plasma, wherein the outflowgas products comprise acetylene and hydrogen; flowing the outflow gasproducts to exit the plasma reaction chamber, whereupon the outflow gasproducts are processed with a set of separation and purification steps2310. The separation and purification steps 2310, comprising the stepsof effluent separation, acetylene separation, and hydrogen separation,yield a set of component gases comprising an acetylene-rich gas stream2312, which stream 2312 then is distributed 2316 so that it enters aprocess for manufacturing acetylene black 2302 b. The separation andpurification steps also produce off-gases such as acetylene byproductsand pure hydrogen that are removed 2314 a from the acetylene-rich stream2312, or are, in whole or in part, rejoined 2314 b to enter themanufacturing process 2302 b with the acetylene-rich stream 2312 asfeedstock for the acetylene decomposition reactor 2318 that producesacetylene black 2330 and hydrogen 2332 from the acetylene in theacetylene-rich stream 2312. The hydrogen that is part of the offgasstream 2314 a produced by the separation and purification steps can beall, or in part, recycled (not shown) back to the beginning of thepathway 2302 a, as a recycled gas stream that becomes one of the rawmaterials 2304 for the plasma-based hydrocarbon processing system. Inembodiments, hydrogen from the offgas stream 2314 a can, all or in part,directly or indirectly, be collected as a desired, final product.

A separation system using adsorbers, as discussed above, is well suitedfor producing an acetylene-rich stream 2312 that can be distributed 2316into the process for manufacturing acetylene black 2302 b. As shown inthis Figure, the separation and purification steps 2310 process theoutflow gas products so that the acetylene-rich stream 2312 can beseparated from the off-gases (whether removed from the system 2314 a orrejoined 2314 b to enter the manufacturing process 2302 b), yieldingjust an acetylene-rich stream 2312 that provides the feed for theacetylene decomposition reactor 2318. The specific nature of theacetylene-rich stream 2312, however, can be engineered to meet the needsof the acetylene decomposition reactor 2318 and related processes, asshown schematically in the process for manufacturing acetylene black2302 b.

In embodiments, it may be advantageous to use an acetylene separator(not shown) to carry out the separation and purification steps 2310,such as a short-cycle TSA with or without a standard TSA, as describedabove. In such an arrangement, the higher acetylenes captured by ashort-cycle TSA (for example, with no standard TSA) can be passed intothe manufacturing process 2314 b to be processed along with theacetylene-rich stream 2312 to reach the acetylene decomposition reactor2318. In embodiments, for example, if the acetylene black produced hasfavorable properties when no higher acetylenes are used, or if theextended regeneration time of a short-cycle TSA operated without a TSAscrubbing step introduces disadvantages, a standard TSA can be operatedbefore the short-cycle TSA so that a substantially pure acetylene-richstream 2312 is used. Other acetylene separation methods that provideacetylene at purities above 90% such as absorption column systems canalso be used. Depending on the quality of acetylene black productdesired, acetylene at lower purities can be used as well, for example byproviding a stream comprising the higher acetylenes captured by ashort-cycle TSA with no standard TSA to enter the manufacturing process2314 b either alone or to be processed along with the acetylene-richstream 2312 to reach the acetylene decomposition reactor 2318.

Optionally, accelerating species can be added to compensate for the lessreactive stream (either stream 2314 b alone or stream 2314 b admixedwith the acetylene-rich stream 2312). Balancing the levels of limitingand accelerating species is important for the production of high qualityacetylene black and hydrogen from an impure acetylene stream. Somelimiting species such as methane, ethylene, and propadiene are found inan impure stream and can decompose endothermically. Other limitingspecies such as hydrogen and nitrogen can be found in an impure stream,but do not permanently decompose. However, limiting species will sapheat from the reaction, changing the character of the acetylene blackproduced; when in excess they can cool the process far enough to haltthe reaction. Thus limiting species are to be avoided in theacetylene-rich stream 2312. Accelerating species in an acetylene mixturewill tend to add heat the reaction and will also change the character ofthe acetylene black produced. When present in excess they can allow thegas mixture to decompose spontaneously or in response to minorprovocation leading to concerns of safety and reliability. For example,accelerating species such as higher acetylenes release more energy thanacetylene as they decompose. Others, such as oxidizers, increase therate of the reaction. Both limiting and accelerating species can bepresent in the feed stream 2312 and balanced against one other forfurther control of the characteristics of the acetylene black produced.

Via the reactions depicted in Pathway 2302 a in FIG. 23 , theplasma-based hydrocarbon processing system produces acetylene andhydrogen in a stoichiometric 1:3 ratio from methane, the primaryconstituent of natural gas. The acetylene decomposition reactionentailed in the manufacture of acetylene black 2302 b produces one molof hydrogen 2332 for each mol of acetylene reacted, along with theacetylene black itself 2330. Therefore, by converting the acetyleneproduced from methane by the plasma-based hydrocarbon processing system(as has been disclosed herein) into hydrogen and acetylene black, thetotal hydrogen produced is increased by a third, to four mols ofhydrogen gas for every two mols of methane. Thus this system isadvantageous for producing hydrogen: besides the hydrogen produced bythe plasma-based hydrocarbon processing system (shown here as thehydrogen-containing offgas that is removed 2314 a from the system andthe hydrogen-containing offgas that is rejoined 2314 b with theacetylene-rich stream 2312 to re-enter the acetylene black manufacturingprocess 2302 b), the acetylene decomposition reactor 2318 producessubstantial quantities of hydrogen 2332, which can be further purifiedif a secondary, pure hydrogen product is desired as a byproduct ofacetylene decomposition or as a primary final product, with anyacetylene black deemed a byproduct.

In embodiments, these systems and methods can be readily adapted forproducing hydrogen as a desired final product, for example, byseparating the hydrogen in the separated offgas 2314 a from theacetylene byproducts. Systems and methods for producing hydrogen as adesired final product are described in more detail with reference toFIG. 24 below. In embodiments, the hydrogen gas produced by thesesystems and methods can in addition or alternatively be recycled intothe plasma-based hydrocarbon processing system, as has been previouslydescribed. Advantageously, in contrast with hydrogen produced by othertechniques such as partial oxidation of methane or natural gas, thecarbon that is liberated from the feedstock in the acetylenedecomposition reactor 2318 is sequestered into a second stablecommodity, acetylene black 2330, instead of being liberated as carbonmonoxide and ultimately as carbon dioxide, both common byproducts ofcertain conventional processes.

In embodiments, a feedstock other than methane can be used to produceacetylene via the plasma-based hydrocarbon processing system asdisclosed herein; with such a feedstock, the ratio of hydrogen toacetylene produced will be less than 3:1 and the relative increase intotal hydrogen production will be greater than one third. Additionally,the acetylene decomposition reactor that produces acetylene black fromthe acetylene-rich feedstock 2312 is permissive of impure acetylenestreams within certain bounds, although the precise composition of thestream can affect the characteristics of the acetylene black product. Apurification system that includes one or more adsorption steps, asdescribed above, allows the careful separation of the ideal mixture ofproducts for hydrogen and acetylene black production.

As mentioned above, the acetylene-rich stream 2312 produced by theseparation and purification steps 2310 is distributed 2316 to reach theacetylene decomposition reactor 2318. The acetylene-rich stream 2312 canbe distributed 2316 for this purpose via direct delivery 2324 (i.e.,without any intermediate diversions or sequestrations of gas); inaddition, or alternatively, the acetylene-rich stream 2312 can bedistributed 2316 for storage 2322, or for a commercialization process2320 such as bottling, with either of these destinations available toprovide feedstock for the acetylene decomposition reactor 2318 (as shownin paths 2326 and 2328). The steps shown by the pathways within 2302 billustrate ways by which acetylene-rich stream 2312 produced by theplasma-based hydrocarbon processing pathway 2302 a can enter theacetylene decomposition reactor 2318. In embodiments, the acetylene canbe bottled 2320, wherein pure acetylene derived from the acetylene-richstream 2312 is stored in commercialsized bottles via dissolving in aliquid media at elevated pressure; bottled acetylene 2320 can be used asa feedstock for the acetylene decomposition reactor 2318, or it can becommercialized separately.

The distribution process 2316 is intended to optimize the utilization ofthe acetylene produced by the plasma-based hydrocarbon processingpathway 2302 a by adjusting the inflow of the acetylene-rich stream 2312produced though the pathway 2302 a to conform to as is required by theacetylene decomposition reactor 2318, for example, via a feedbackmechanism whereby the inflow of the acetylene-rich stream 2312 isincreased or decreased depending on a measurement for requisiteacetylene that is provided by the acetylene black manufacturing system.

As described above, these systems and methods can be optimized tomaximize the amount and purity of hydrogen that is formed, hereillustrated in this Figure as the hydrogen product 2332 of the acetylenedecomposition reactor 2318, and as the pure hydrogen separable from theoffgas removed as 2314 a. More detail about the disposition of thehydrogen separable from the offgas removed as 2314 a is provided below,with reference to FIG. 24 .

FIG. 24 shows in more detail how the systems and methods disclosedherein can be integrated with systems and processes for producinghydrogen as a separate, commercializable product. This Figureillustrates an embodiment of the systems disclosed herein, showing howthese the systems and methods produce a highly purified acetylene thatis suitable for direct and/or controllable delivery to the manufacturingprocesses, such as the manufacturing of acetylene black described aboveand/or the manufacturing of hydrogen gas. The systems and methodsdisclosed herein can optimize processes for producing hydrogen inconcert with the manufacturing of carbon-containing products such asacetylene black.

FIG. 24 shows an embodiment of a hydrogen and acetylene productionsystem 2400, which initially produces hydrogen gas and acetylene in aplasma-based hydrocarbon subsystem 2402 substantially similar to thoseplasma-based hydrocarbon subsystems described previously. The hydrogengas produced by the plasma-based hydrocarbon subsystem 2402 can berecycled or commercialized separately, as described below. The acetyleneproduced by the plasma-based hydrocarbon subsystem 2402 can becommercialized separately or can be used as the feedstock for a system2450 producing acetylene black and additional hydrogen similar to thesystem described above and shown in FIG. 23 .

In more detail with reference to FIG. 24 , the plasma-based hydrocarbonprocessing system 2402 yields a highly purified acetylene product 2408that can be delivered into the system 2450 for manufacturing acetyleneblack. In the depicted embodiment, the plasma-based hydrocarbonprocessing system 2402 comprises a hydrocarbon inflow stream 2410 (e.g.,natural gas) and a recycled gas stream 2412, a microwave reactor 2414comprising a plasma reaction chamber (not shown) into which thehydrocarbon inflow stream 2410 and the recycled gas stream 2412 aredelivered, wherein they are energized by a microwave subsystem (notshown) to form a plasma that yields chemical products that emerge fromthe plasma chamber to form an outflow stream 2418 of outflow gasproducts, all as have been described in detail in previous Figures. Inthe depicted embodiment, the outflow stream 2418 is subjected to furtherprocessing and separation, including passage through a set of separatorsubsystems.

The set of separator subsystems, all of which have been describedpreviously in more detail, include, in the depicted embodiment: (i) aneffluent separator 2420 for the removal of higher acetylenes andaromatic impurities (C₃ ⁺) (using for example a temperature swingadsorber or a prescrubber), yielding a purified effluent stream 2422;(ii) an acetylene separator 2424 for the separation of the highlypurified acetylene product 2408 from the purified effluent stream 2422via acetylene purification columns or the like, following which aremaining effluent stream 2428 emerges from the acetylene separator; and(iii) a hydrogen separator 2430 (e.g., a pressure swing absorber, atemperature swing adsorber, or a membrane separator). The subsystems canbe arranged in the order shown in FIG. 24 , where the hydrogen separator2430 is downstream from the acetylene separator 2424 and thus separateshydrogen as a highly purified hydrogen product from a remaining effluentstream 2428 from which the highly purified acetylene product 2408 hasalready been removed. In other embodiments, the hydrogen separator 2430can be positioned upstream from the acetylene separator 2424, so thatthe hydrogen is removed from the purified effluent stream 2422 beforethe latter enters the acetylene separator 2424. Any hydrogen removed bythe hydrogen separator 2430 (whether upstream from the acetyleneseparator 2424 or downstream from it) can be either isolated from thesystem as an integrated hydrogen stream to be used in integratedmanufacturing or chemical processing, or can be isolated from the systemas an external hydrogen stream for separate commercialization, storageor disposal, or can be recycled into the system as a recycled hydrogenstream, all as described below.

In more detail, FIG. 24 depicts one possible sequencing of the separatorsteps and subsystems. In the depicted embodiment, the remaining effluentstream 2428 is divided by a divider 2426 into two streams, 2428 a and2428 b. The first remaining effluent stream portion 2428 a undergoesfurther treatment in the hydrogen separator 2430, with the purifiedhydrogen product 2432 being separated therefrom, yielding a residual gasstream 2436. The second remaining effluent stream portion 2428 b isdiverted by the divider 2426 before entering the hydrogen separator 2430and instead is recycled, forming a recycled gas stream 2412 (eitheralone or, as depicted, in conjunction with other gas streams such as theresidual gas stream 2436 exiting the hydrogen separator 2430); therecycled gas stream 2412 is available for use in the microwave reactor2414 as described previously. In embodiments, the divider 2426 can be avalve or other set of pathways that controllably directs the flow of theremaining effluent stream 2428 into one or both of the first remainingeffluent stream portion 2428 a and the second remaining effluent streamportion 2428 b. In embodiments, the divider 2426 is an optional feature.The residual gas stream 2436 can be used to form the recycled gas stream2412, either blended with other recyclable gas streams such as thesecond remaining effluent stream 2428 b (as depicted in this Figure)and/or combined with other gas streams (not shown), or used alone toform the recycled gas stream 2412.

Purified hydrogen product 2432 exiting the hydrogen separator 2430 canbe directed in one or more outflow streams 2432 a, 2432 b, and 2432 c.The outflow gas streams 2432 a and/or 2432 c can be isolated from theoverall processing system 2402, to be used in other manufacturingprocesses (not shown) that can be integrated with and/or in fluidcommunication with the overall system 2402, or to be segregated from theoverall system 2402 as separate commercial products for separate sale,storage, or disposal. In more detail, one of the streams, 2432 a, is anintegrated hydrogen stream to be used in other integrated processes (notshown) for which hydrogen can be used as a feedstock, for examplechemical manufacturing processes. As an example, the purified hydrogenproduct 2432 can be directed to form an integrated hydrogen stream 2432a to be combined with the purified acetylene product 2408 in otherintegrated processes such as have been described previously, e.g., forvitamin manufacturing. In embodiments, the purified hydrogen product2432 can be isolated as an external hydrogen stream 2432 c for separatesale, storage, or disposal. Instead of or in addition to being isolated,as shown for streams 2432 a and 2432 c, the purified hydrogen product2432 can be directed as a recycled hydrogen stream 2432 b to form acomponent of the recycling gas stream 2412 by merging, for example, withthe residual gas stream 2436. It is understood that the purifiedhydrogen product 2432 can be directed into one or more of thesubpathways 2432 a, 2432 b, and 2432 c, in accordance with commercialrequirements, including those situations in which the system 2402 isintegrated with other manufacturing or storage subsystems (not shown).In embodiments, a controller (not shown) directs the purified hydrogenproduct 2432 in appropriate quantities along one or more preselectedsubpathways 2432 a, 2432 b, and/or 2432 c.

In embodiments, recycling the hydrogen into the processing system 2402at any point in the system that is downstream from the microwave reactorcan be implemented as an advantageous alternative to recycling into orprior to the microwave reactor, so that impurities or contaminants inthe recycled stream can be removed by the existing separation processes,and so that the hydrogen can be further purified by the existingpurification equipment. In other embodiments, the hydrogen may be ofsufficient quality so that it can be recycled into the microwave reactorto be used immediately or after being placed in a temporary storage orholding tank. As previously described, the hydrogen can be isolatedinstead of recycled, so that it is directed to another integratedindustrial use 2342a or it is directed off-site 2432cfor sale or usage,either as a gas or liquid.

Regardless of the use of the hydrogen as a desired product (as in 2432 aor 2432 c), it can optionally be further purified using purificationprocesses, such as membranes, PSAs, etc. (any process known in the art)so that it is suitable for its intended use. In embodiments, thehydrogen, whether further purified or not, can be directly used in achemical synthesis process, used as fuel for hydrogen fuel cells,burned, etc., as suggested by the subpath 2432 c. In embodiments, all orpart of this hydrogen stream designated for use as an integratedhydrogen stream 2432 a or an external hydrogen stream 2432 c, whetherfurther purified or not, can also be stored (either as a gas orcompressed into a liquid), or be transported or distributed by pipelineor container to a separate location, where the product is employed forits intended use.

As shown in FIG. 24 , the acetylene-rich stream 2408 produced by theacetylene separator 2424 is distributed by a controller 2440 for furtheruse in the process of manufacturing acetylene black and hydrogen 2450.The controller 2440 permits the distribution of the acetylene-richstream 2408 in accordance with the requirements of the manufacturingsystem, whereby the acetylene-rich stream 2408 ultimately arrives at theacetylene decomposition reactor 2446, which separates acetylene into thecomponent products of acetylene black 2448 and hydrogen 2460. Similar tothose systems and methods illustrated in FIG. 23 , the controller 2440is intended to optimize the utilization of the highly purified acetyleneproduced by the plasma-based hydrocarbon processing pathway 2402 byadjusting the inflow of the acetylene-rich stream 2408 produced thoughthe pathway 2402 to conform to the needs of the process formanufacturing acetylene black and hydrogen 2450, for example, via afeedback mechanism whereby the inflow of the acetylene-rich stream 2408is increased or decreased depending on a measurement for requisiteacetylene that is provided by the acetylene decomposition reactor 2446.

The acetylene-rich stream 2408 can reach the acetylene decompositionreactor 2446 via direct delivery 2442 (i.e., without any intermediatediversions or sequestrations of gas); in addition, or alternatively, theacetylene-rich stream 2408 can be distributed for storage 2456, or for acommercialization process 2452 such as bottling, with either of thesedestinations available to provide the acetylene-rich feedstock for usein the acetylene decomposition reactor 2446.

Similar to the system depicted in FIG. 23 , the integrated hydrogen andacetylene production system shown in FIG. 24 is advantageous forproducing hydrogen. Besides the hydrogen 2432 produced by theplasma-based hydrocarbon processing system, the acetylene decompositionreactor 2446 produces substantial quantities of hydrogen 2460, which canbe further purified if a secondary, pure hydrogen product is desired asa byproduct of acetylene decomposition, or as a primary final product,with any acetylene black deemed a byproduct.

In embodiments, these systems and methods can be readily adapted forproducing hydrogen as a desired final product. For example, the hydrogen2432 produced by the plasma-based hydrocarbon processing system can bejoined with the hydrogen 2460 produced by the acetylene decompositionreactor 2446, for any previously-described hydrogen use. For example,the hydrogen 2432 and 2460 produced from both sources can providefeedstock for a separate, integrated chemical processing plant (notshown). As another example, the hydrogen 2432 and 2460 produced by bothsources can be bottled or otherwise transported to end-users, or can bedistributed into the infrastructure that feeds hydrogen-equipped fillingstations, such as can be used by hydrogen-powered vehicles. Otherdirect-to-consumer uses for the hydrogen 2432 and 2460 produced by thesesystems and methods can be readily envisioned by artisans in the field,with such uses expanding as the hydrogen economy gains a greaterpresence in the marketplace. In other embodiments, the hydrogen gasproduced by these systems and methods can, in addition or alternatively,be recycled into the plasma-based hydrocarbon processing system, as hasbeen previously described. Advantageously, in contrast with hydrogenproduced by other techniques such as partial oxidation of methane ornatural gas, the carbon (i.e., acetylene black 2448) that is liberatedfrom the feedstock in the acetylene decomposition reactor 2446 issequestered into a second stable commodity, acetylene black 2448,instead of being liberated as carbon monoxide and ultimately as carbondioxide, both common byproducts of certain conventional processes.

EXAMPLES Example 1

A flow of precursor gas, comprised of 60 standard liters per minute of99.9% purity methane, 90 standard liters per minute of 99.9% purityhydrogen, and 6 standard liters per minute of nitrogen, was suppliedthrough a gas injector apparatus similar to that described in FIGS. 4Aand 4B, into an 50 mm outer diameter, 45 mm inner diameter quartz tubekept at a pressure of 70 Torr. The precursor gas was subj ected to 19kWof incident 915 MHz microwave power in a plasma reactor apparatussimilar to that described in FIG. 3 . 95.7% of the methane contained inthe precursor gas was converted to hydrogen and hydrocarbon products.The hydrocarbon composition of the outflow gas leaving the reactor isdescribed in Table 6 below, as analyzed by a gas chromatograph.

TABLE 6 Component Mol % Acetylene 15.12 Hydrogen 82.97 Methane 1.41Ethylene 0.14 Propane 0.01 Propadiene 0.01 Diacetylene 0.29 VinylAcetylene 0.03 Benzene 0.02 Carbon Solids and higher-order hydrocarbonsTrace

The outflow gas from the reactor was passed through an air-cooled heatsink and then passed through corrugated-paper filters before exiting thevacuum pump. The outflow gas then passed through a cold trap operatingat 10° C. and additional filter.

A portion of outflow gas was then passed through an adsorption columncontaining high surface area activated carbon. Outflow gas compositionat the adsorption column exit is shown in Table 7 below.

TABLE 7 Component Mol Percent before Adsorption Mol Percent afterAdsorption Acetylene 15.12 15.17 Hydrogen 82.97 83.25 Methane 1.41 1.41Ethylene 0.14 0.14 Propane 0.01 0.1 Propadiene 0.01 0.1 Di acetylene0.29 0 Vinyl Acetylene 0.03 0 Benzene 0.02 0 Carbon Solids Trace 0Higher Order Hydrocarbons Trace 0

After leaving the adsorption column, a portion of the outflow gas wasthen passed through an absorption column. A solvent, N-Methylpyrrolidone, was flowed counter-currently to the outflow gas topreferentially absorb acetylene. Exiting the absorption column, thesolvent with the absorbed acetylene was pumped into a second column forrestoring the solvent and heated to 120-140° C. In the second column,the acetylene and associated gases were removed from the solvent as apurified product gas stream and the restored solvent was recycled intothe system. Table 8 below shows the composition of the purified productgas stream emanating from the second column.

TABLE 8 Component Mol Percent Acetylene 98.764 Hydrogen 0.774 Methane0.211 Ethylene 0.083 Ethane 0.002 Propylene 0.042 Diacetylene 0.002Vinyl Acetylene 0.006 Carbon Dioxide 0.115 Toluene 0.001

Example 2

A flow of precursor gas, comprised of 20 standard liters per minute of99.9% purity methane, 20 standard liters per minute of ethane, 95standard liters per minute of 99.9% purity hydrogen, and 6 standardliters per minute of nitrogen was supplied through a plasma reactorapparatus as described in Example 1 and reacted with 18 kW of incident915 MHz microwave power using the plasma reactor apparatus used inExample 1. 97.9% of the methane and ethane contained feed gas wasconverted to hydrogen and hydrocarbon products. The hydrocarboncomposition of the outflow gas from the reactor is described in Table 9below, as analyzed by a gas chromatograph.

TABLE 9 Component Mol % Acetylene 16.70 Hydrogen 72.73 Methane 0.75Ethylene 0.35 Propane 0.01 Propadiene 0.01 Diacetylene 0.38 VinylAcetylene 0.05 Benzene 0.03 Carbon Solids Trace Higher-Order HCs

Example 3

A flow of precursor gas, comprised of 110 standard liters per minute of99.9% purity methane and 11 standard liters per minute of nitrogen, wassupplied through a gas injector apparatus, similar to that described inFIGS. 4A and 4B, into an 80 mm outer diameter, 75 mm inner diameterquartz tube. The precursor gas was subjected to 11 kW of incident 915MHz microwave power in a plasma reactor apparatus as described in FIG. 3. 50.7% of the methane contained in the precursor gas was converted tohydrogen and hydrocarbon products. 7% of the converted methane yieldedcarbon solids and polycyclic aromatic hydrocarbons. 76% of the convertedmethane yielded acetylene.

Example 4

A flow of precursor gas, comprised of 100 standard liters per minute of99.9% purity methane, 160 standard liters per minute of 99.9% purityhydrogen, and 10 standard liters per minute of nitrogen, was suppliedthrough a gas injector apparatus similar to that described in FIGS. 4Aand 4B, into an 50 mm outer diameter, 45 mm inner diameter quartz tubekept at 70 Torr. The precursor gas was subjected to 29 kW of incident915 MHz microwave power in a plasma reactor apparatus similar to thatdescribed in FIG. 3 . 90.3% of the methane contained in the precursorgas was converted to hydrogen and hydrocarbon products. The hydrocarboncomposition of the outflow gas leaving the reactor is described in Table10 below.

TABLE 10 Component Mol % Hydrogen 83.42729 Methane 2.99563 Propane0.010008 Propylene 0.010008 Propadiene 0.060046 Methyl Acetylene0.010008 1,3-butadiene 0 Vinyl Acetylene 0.020015 Diacetylene 0.253528Ethylene 0.143443 Ethane 0 Acetylene 13.05334 Benzene 0.016679 Toluene 0

Example 5

A flow of precursor gas, comprised of 130 standard liters per minute of99.9% purity methane, and 13 standard liters per minute of nitrogen, wassupplied through a gas injector apparatus similar to that described inFIGS. 4A and 4B, into an 80 mm outer diameter, 75 mm inner diameterquartz tube kept at 48 Torr. The precursor gas was subjected to 24.3 kWof incident 915 MHz microwave power in a plasma reactor apparatussimilar to that described in FIG. 3 . 85.2% of the methane contained inthe precursor gas was converted to hydrogen and hydrocarbon products.

Example 6

A flow of precursor gas, comprised of 74 standard liters per minute of99.9% purity methane, 40 standard liters per minute of 99.9% purityhydrogen, and 88 standard liters per minute of nitrogen, was suppliedthrough a gas injector apparatus similar to that described in FIGS. 4Aand 4B, into an 80 mm outer diameter, 75 mm inner diameter quartz tubekept at 70 Torr. The precursor gas was subjected to 23.9 kW of incident915 MHz microwave power in a plasma reactor apparatus similar to thatdescribed in FIG. 3 . 95.1% of the methane contained in the precursorgas was converted to hydrogen and hydrocarbon products.

Example 7

A flow of precursor gas, comprised of 47 standard liters per minute of99.9% purity methane, 110 standard liters per minute of 99.9% purityhydrogen, and 5 standard liters per minute of nitrogen, was suppliedthrough a gas injector apparatus similar to that described in FIGS. 4Aand 4B, into an 80 mm outer diameter, 75 mm inner diameter quartz tubekept at 65 Torr. The precursor gas was subjected to 15.6 kW of incident915 MHz microwave power in a plasma reactor apparatus similar to thatdescribed in FIG. 3 . 89.7% of the methane contained in the precursorgas was converted to hydrogen and hydrocarbon products.

Example 8

A flow of precursor gas, comprised of 90 standard liters per minute of99.9% purity methane, 135 standard liters per minute of 99.9% purityhydrogen, and 9 standard liters per minute of nitrogen, was suppliedthrough a gas injector apparatus similar to that described in FIGS. 4Aand 4B, into an 38 mm outer diameter, 35 mm inner diameter quartz tubekept at 105 Torr. The precursor gas was subjected to 25 kW of incident915 MHz microwave power in a plasma reactor apparatus similar to thatdescribed in FIG. 3 . 92.0% of the methane contained in the precursorgas was converted to hydrogen and hydrocarbon products.

Example 9

A flow of precursor gas, comprised of 15 standard liters per minute of99.9% purity butane, 90 standard liters per minute of 99.9% purityhydrogen, and 6 standard liters per minute of nitrogen, was suppliedthrough a gas injector apparatus similar to that described in FIGS. 4Aand 4B, into an 50 mm outer diameter, 45 mm inner diameter quartz tubekept at 50 Torr. The precursor gas was subjected to 17.7 kW of incident915 MHz microwave power in a plasma reactor apparatus similar to thatdescribed in FIG. 3 . 100% of the butane contained in the precursor gaswas converted to hydrogen and hydrocarbon products with a 0.6% methaneyield.

Example 10

A flow of precursor gas, comprised of 30 standard liters per minute of99.9% purity ethane, 90 standard liters per minute of 99.9% purityhydrogen, and 6 standard liters per minute of nitrogen, was suppliedthrough a gas injector apparatus similar to that described in FIGS. 4Aand 4B, into an 50 mm outer diameter, 45 mm inner diameter quartz tubekept at 126 Torr. The precursor gas was subjected to 16 kW of incident915 MHz microwave power in a plasma reactor apparatus similar to thatdescribed in FIG. 3 . 100% of the ethane contained in the precursor gaswas converted to hydrogen and hydrocarbon products with 3.3% methaneyield. The hydrocarbon composition of the outflow gas leaving thereactor is described in Table 11 below.

TABLE 11 Component Mol % acetylene 18.34358 hydrogen 79.93364 methane0.824195 ethane 0.003651 ethylene 0.383346 propane 0.006845 propadiene0.008215 propylene 0 diacetylene 0.412097 vinyl acetylene 0.054307methyl acetylene 0 benzene 0.028751 toluene 0.001369

Example 11

A flow of precursor gas, comprised of 8.6 standard liters per minute of99.9% purity propane, 8.6 standard liters per minute of 99.9% puritybutane, 88 standard liters per minute of 99.9% purity hydrogen, and 6standard liters per minute of nitrogen, was supplied through a gasinjector apparatus similar to that described in FIGS. 4A and 4B, into an50 mm outer diameter, 45 mm inner diameter quartz tube kept at 70 Torr.The precursor gas was subjected to 16 kW of incident 915 MHz microwavepower in a plasma reactor apparatus similar to that described in FIG. 3. 100% of the ethane contained in the precursor gas was converted tohydrogen and hydrocarbon products with a 3.2% methane yield. Thehydrocarbon composition of the outflow gas leaving the reactor isdescribed in Table 12 below.

TABLE 12 Component Mol % Acetylene 20.33077 Hydrogen 77.56967 Methane1.155769 Ethane 0 Ethylene 0.293664 Propane 0.008498 propadiene 0.013692propylene 0 diacetylene 0.549557 vinyl acetylene 0.046269 methylacetylene 0 Benzene 0.030688 Toluene 0.001416

Example 12

A plasma reactor system as described in Example 1 that produces 250liters of outflow gas per minute was used. After the vacuum pump in thesystem, solid carbon byproducts were removed with a simple in-linefilter. Liquid hydrocarbon condensates containing greater than 14 carbonatoms were separated from the stream in a cold trap operating at -20° C.No further hydrocarbons were removed, and the outflow was directlypassed through a stainless-steel vessel with an internal diameter of 8inches containing 0.4 kg of blank 100-200 mesh α-alumina mixed with 1.8kg of 100-200 mesh α-alumina doped with 3 wt% metallic palladium and 4wt% metallic silver. The catalyst bed was maintained at 350° C. withinternal, open-loop water cooling system. A gas mixture was obtainedthat contains 50% hydrogen, 11% ethylene, 0.5% ethane and 38.5% methane;acetylene content in the gas mixture was deliberately kept below 100ppm.

Example 13

A plasma reactor system as described in Example 1 was used. A stream of1 liter of outflow gas per minute was split off and processed further asdescribed in this example. After the vacuum pump, solid carbonbyproducts were removed with a ceramic, regenerative filter. Liquidhydrocarbon condensates containing greater than 10 carbon atoms wereseparated from the stream in a cold trap operating at -30° C.Afterwards, the outflow gas was passed through a stainless-steel vesselcontaining 20 grams high-surface area activated carbon, doped with 0.01%metallic palladium. The outflow gas at this point contained 85%hydrogen, 8% acetylene, 4% ethylene, and 0.6% vinyl acetylene andbalance methane. The vinyl acetylene was removed by bubbling through a500 mL vessel containing 300 mL of concentrated sulfuric acid at roomtemperature, then through a vessel containing 100 mL room temperaturewater to trap the volatized sulfuric acid. Finally, the gas stream wasdried by passing through 10 grams of calcium sulfate desiccant.

Example 14

Precursor gas, comprised of 303 standard liters per minute of utilitynatural gas (having a composition of about 96.7% methane, about 2.7%ethane, and about 0.4% nitrogen), 628 standard liters per minute of99.9% purity hydrogen, and 31 standard liters per minute of nitrogen,was supplied through a gas injector apparatus, similar to that describedin FIGS. 4A and 4B, into a 50 mm outer diameter, 45 mm inner diameterquartz tube that was maintained at 260 mbara. The precursor gas wassubjected to 98 kW of incident 915 MHz microwave power in a plasmareactor apparatus as described in FIG. 3 . 90.6% of the hydrocarbonscontained in the precursor gas was converted to hydrogen and hydrocarbonproducts. The reactor effluent gas composition excluding nitrogen isdescribed in Table 13, as analyzed by a gas chromatograph.

TABLE 13 Component Mol% Hydrogen 84.5% Methane 2.74% Ethylene 0.168%Acetylene 12.2% Propylene 0.046% Methyl Acetylene 0.030% Propadiene0.014% Vinyl Acetylene 0.046% Di acetylene 0.284% Benzene 0.017% Toluene0.007%

The outflow gas from the reactor was passed through an air-cooled heatsink and then passed through corrugated-paper filters before exiting thevacuum pump. The outflow gas then passed through a cold trap operatingat 10° C. and additional filter.

EQUIVALENTS

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims. Unless otherwise indicated, allnumbers expressing reaction conditions, quantities, amounts, ranges andso forth, as used in this specification and the claims are to beunderstood as being modified in all instances by the term “about.”Accordingly, unless indicated to the contrary, the numerical parametersset forth herein are approximations that can vary depending upon thedesired properties sought to be obtained by the present invention.

Furthermore, the invention encompasses all variations, combinations, andpermutations in which one or more limitations, elements, clauses, anddescriptive terms from one or more of the listed claims is introducedinto another claim. For example, any claim that is dependent on anotherclaim can be modified to include one or more limitations found in anyother claim that is dependent on the same base claim. Where elements arepresented as lists, e.g., in Markush group format, each subgroup of theelements is also disclosed, and any element(s) can be removed from thegroup. It should it be understood that, in general, where the invention,or aspects of the invention, is/are referred to as comprising particularelements and/or features, certain embodiments of the invention oraspects of the invention consist, or consist essentially of, suchelements and/or features. For purposes of simplicity, those embodimentshave not been specifically set forth in haec verba herein. It is alsonoted that the terms “comprising” and “containing” are intended to beopen and permits the inclusion of additional elements or steps. Whereranges are given, endpoints are included. Furthermore, unless otherwiseindicated or otherwise evident from the context and understanding of oneof ordinary skill in the art, values that are expressed as ranges canassume any specific value or sub-range within the stated ranges indifferent embodiments of the invention, to the tenth of the unit of thelower limit of the range, unless the context clearly dictates otherwise.

1. A method for processing a methane-containing inflow gas to produceoutflow gas products, comprising directing the methane-containing inflowgas into a system comprising: a gas delivery subsystem, a plasmareaction chamber, a microwave subsystem, a vacuum subsystem, and aneffluent separation and disposal subsystem; i. wherein the gas deliverysubsystem is in fluid communication with the plasma reaction chamber anddirects the methane-containing inflow gas into the plasma reactionchamber, the gas delivery subsystem comprising a delivery conduit and agas injector, wherein the gas injector comprises an injector bodycomprising two or more separate gas feeds, a first gas feed conveyingthe methane-containing inflow gas into the plasma reaction chamberthrough a first set of one or more nozzles, and a second gas feedconveying a hydrogen-rich reactant gas into the plasma reaction chamberthrough a second set of one or more nozzles, wherein the deliveryconduit is in fluid communication with the gas injector, wherein thedelivery conduit comprises a feed gas conveying circuit that deliversthe methane-containing inflow gas into the gas injector, and wherein thedelivery conduit further comprises an auxiliary gas conveying circuitthat delivers the hydrogen-rich reactant gas into the gas injector, andwherein the methane-containing inflow gas is delivered into the gasinjector through the gas injector and into the plasma reaction chamberthrough a first pathway, and the hydrogen-rich reactant gas is deliveredinto the gas injector, through the gas injector, and into the plasmareaction chamber through a second pathway that is separate from thefirst pathway; ii. wherein the plasma reaction chamber is disposedwithin an elongate reactor tube, the elongate reactor tube having aproximal end and a distal end and being dimensionally adapted forinteraction with the microwave subsystem, iii. wherein the microwavesubsystem comprises an applicator that interacts with the elongatereactor tube by directing the microwave energy into the plasma reactionchamber, wherein the plasma reaction chamber is disposed in a region ofthe elongate reactor tube that passes through the applicator andintersects it perpendicularly, wherein the microwave subsystem producesmicrowave energy and directs the microwave energy into the plasmareaction chamber to energize the methane-containing inflow gas and thehydrogen-rich reactant gas within the region of the elongate reactortube to form a non-thermal plasma, and wherein the non-thermal plasmatransforms the methane in the methane-containing inflow gas and thehydrogen in the hydrogen-rich reactant gas into the outflow gasproducts, wherein the outflow gas products comprise acetylene andhydrogen; wherein the outflow gas products flow within the plasmareaction chamber towards the distal end of the elongate reactor tube andemerge from the distal end to form an effluent stream that enters aneffluent separation and disposal subsystem in fluid communication withthe elongate reactor tube, iv. wherein the effluent separation anddisposal subsystem comprises at least one of a hydrogen separationsubsystem for removing the hydrogen from the effluent stream, anacetylene separation subsystem for removing the acetylene from theeffluent stream, and a temperature swing adsorber for removing higheracetylenes from the effluent stream, and v. wherein the vacuum subsystemmaintains a first reduced pressure environment for the outflow gasproducts passing through the effluent separation and disposal system andwherein the first reduced pressure environment is between about 120 andabout 280 Torr.
 2. The method of claim 1, wherein the hydrogen-richreactant gas comprises a recycled gas formed from a portion of theoutflow gas products and wherein the recycled gas is delivered through arecycled gas conveying circuit into the auxiliary gas conveying circuitto form at least a portion of the hydrogen-rich reactant gas that entersinto the gas injector.
 3. The method of claim 2, wherein thehydrogen-rich reactant gas consists essentially of hydrogen.
 4. Themethod of claim 1, wherein the two or more separate gas feeds areco-axially arranged.
 5. The method of claim 1, wherein the elongatereactor tube comprises a proximal portion at the proximal end, whereinthe gas injector conveys the methane-containing inflow gas and thehydrogen-rich reactant gas into a proximal portion, and wherein themethane-containing inflow gas and the hydrogen-rich reactant gas flowdistally therefrom towards the plasma reaction chamber.
 6. The method ofclaim 1, wherein at least one of the one or more nozzles in the firstset of one or more nozzles or the second set of one or more nozzles isoriented at an angle to a longitudinal axis of the plasma reactionchamber or at an angle to a transverse axis of the plasma reactionchamber.
 7. The method of claim 1, wherein at least one of the one ormore nozzles in the first set of one or more nozzles or the second setof one or more nozzles is oriented at an angle to a longitudinal axis ofthe injector body or at an angle to a transverse axis of the injectorbody.
 8. The method of claim 1, wherein the methane-containing inflowgas entering the plasma reaction chamber from the first set of one ormore nozzles and the hydrogen-rich reactant gas entering the plasmareaction chamber from the second set of one or more nozzles create avortex flow within the plasma reaction chamber.
 9. The method of claim1, wherein the hydrogen separation subsystem is downstream from theacetylene separation subsystem and in fluid communication therewith. 10.The method of claim 1, wherein the hydrogen separation subsystem is influid communication with a recycled gas conveying circuit, and whereinat least a portion of hydrogen removed from the effluent stream by thehydrogen separation subsystem is recycled into the recycled gasconveying circuit and into the auxiliary gas conveying circuit to format least a portion of the hydrogen-rich reactant gas that enters the gasinjector.
 11. The method of claim 1, wherein the acetylene separationsubsystem and the hydrogen separation subsystem are downstream from thetemperature swing adsorber.
 12. The method of claim 11, wherein thehydrogen separation subsystem is downstream from the acetyleneseparation subsystem.
 13. The method of claim 1, wherein the effluentseparation and disposal subsystem comprises at least two of thefollowing: a hydrogen separation subsystem for removing hydrogen fromthe effluent stream, an acetylene separation subsystem for removingacetylene from the effluent stream, and a temperature swing adsorber forremoving higher acetylenes from the effluent stream.
 14. The method ofclaim 13, wherein the effluent separation and disposal subsystemcomprises the hydrogen separation subsystem for removing hydrogen fromthe effluent stream, the acetylene separation subsystem for removingacetylene from the effluent stream, and the temperature swing adsorberfor removing higher acetylenes from the effluent stream.
 15. The methodof claim 1, wherein the effluent separation and disposal subsystemfurther comprises a filter for removal of carbon solids upstream of theacetylene separation subsystem.
 16. The method of claim 15, wherein theeffluent separation and disposal subsystem further comprises a cold trapfor removing higher order hydrocarbons as condensates.
 17. The method ofclaim 16, wherein the acetylene separation subsystem and the hydrogenseparation subsystem are downstream from the temperature swing adsorber.18. The method of claim 17, wherein the hydrogen separation subsystem isdownstream from the acetylene separation subsystem.
 19. The method ofclaim 1, wherein the gas delivery subsystem conveys themethane-containing inflow gas and the hydrogen-rich reactant gas intothe plasma reaction chamber such that the ratio of the methane to thehydrogen is about 1:1-3.
 20. The method of claim 19, wherein the ratiois about 1:1-2.
 21. The method of claim 19, wherein the ratio is about1:1.5.
 22. The method of claim 1, wherein the vacuum subsystem furtherproduces a second reduced pressure environment within the elongatereactor tube and/or produces a third reduced pressure environment forthe gas delivery subsystem.
 23. The method of claim 22, wherein thevacuum subsystem produces both the second and the third reduced pressureenvironments.
 24. The method of claim 22, wherein the second and thirdreduced pressure environments are each independently between about 120to about 280 Torr.
 25. The method of claim 23, wherein the second andthird reduced pressure environments are each independently between about120 to about 280 Torr.
 26. The method of claim 23, wherein the firstreduced pressure environment has a pressure that is at least about 10%higher than the pressure in the second reduced pressure environmentand/or the third reduced pressure environment.
 27. The method of claim26, wherein the pressure in the second reduced pressure environment andthe third reduced pressure environment is each independently betweenabout 120 and about 280 Torr.
 28. The method of claim 23, wherein theeach of the pressures differ by less than about 10%.